Retardation plate, optical member, and display device

Abstract

To provide a retardation plate with which orientation is good and heat resistance and light fastness are improved, an optical member using the retardation plate, and a display device.SOLUTION: Provided is a retardation plate including a positive C-type retardation layer, and a positive A-type retardation layer located directly adjacent to the positive C-type retardation layer and containing the cured substance of a polymerizable liquid crystal composition, wherein the positive C-type retardation layer contains an optical alignment component, and the polymerizable liquid crystal composition included in the positive A-type retardation layer exhibits reverse wavelength dispersion. The retardation plate satisfies the conditions below. (1): A birefringence Δn in the thickness direction of the positive C-type retardation layer in wavelength 550 nm is 0.080 or less. (2): An optical alignment component exists on the surface of the positive C-type retardation layer, on the side not directly in contact with the positive A-type retardation layer. (3): The absolute value ΔRth of a change amount of out-of-plane phase difference in wavelength 550 nm before and after the heat resistance test of a laminated body of the positive C-type retardation layer and the positive A-type retardation layer is 15 nm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a retardation plate, an optical member, and a display device that use a positive C-type retardation layer that functions as both an alignment layer and a retardation layer in one layer. [Background technology]

[0002] Optical films used in image display devices and the like include retardation plates that provide a desired phase difference to incident light using a retardation layer. For example, in organic electroluminescence (organic EL) display devices, a quarter-wave retardation plate is used as a circular polarizer in combination with a linear polarizer, and functions as an anti-reflection film for external light. Furthermore, in liquid crystal display devices such as IPS mode, a retardation plate that combines a positive A plate with positive A characteristics and a positive C plate with positive C characteristics has been used as part of a polarizing compensation film to enhance contrast when viewed from an oblique direction (for example, Patent Document 1).

[0003] Conventionally, the positive A plate and the positive C plate are laminated together using an adhesive layer or the like. As display devices become thinner, there is a demand for thinner retardation plates, such as broadband quarter-wave retardation plates that are constructed by combining retardation plates, while maintaining performance, and for more efficient manufacturing processes.

[0004] With the aim of reducing the thickness of the retardation plate, Patent Documents 2 to 6 describe optical laminates in which a positive C plate and a positive A plate are laminated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4592005 [Patent Document 2] Japanese Patent Publication No. 2022-003361 [Patent Document 3] International Publication No. 2022 / 018995 [Patent Document 4] International Publication No. 2021 / 167075 [Patent Document 5] International Publication No. 2022 / 071410 [Patent Document 6] International Publication No. 2022 / 158555 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Documents 2 to 6, the positive A-type retardation layer is laminated directly on the positive C-type retardation layer for the purpose of reducing the thickness of the retardation plate. However, the positive C-type retardation layer described in Patent Document 2 is formed using a photosensitive side-chain liquid crystal polymer containing a liquid crystal component exhibiting vertical alignment and a photoalignable component in the same polymer, and has a problem in that it is poor in heat resistance and light resistance and is prone to fluctuation in optical properties. In addition, the positive C-type retardation layer described in Patent Document 3 tends to have poor alignment compared to the positive A-type retardation layer that is directly laminated thereon and exhibits reverse wavelength dispersion, and further tends to have poor heat resistance and heat and light resistance, resulting in problems such as easily fluctuating optical properties. Furthermore, in the positive C-type retardation layers described in Patent Documents 4 and 5, the photo-alignment component is locally unevenly distributed on the surface side of the positive C-type retardation layer directly adjacent to the positive A-type retardation layer, and therefore, the optical properties are easily changed by light irradiation due to the influence of the photosensitive photo-alignment component, resulting in poor heat resistance and light resistance, and the optical properties are easily changed. Furthermore, the positive C-type retardation layer described in Patent Document 6 has a problem in that it has low vertical alignment property, and when a composition for a positive A-type retardation layer exhibiting reverse wavelength dispersion is coated on a positive C-type retardation layer, the alignment property of the positive A-type retardation layer is reduced. Since a liquid crystal compound exhibiting reverse wavelength dispersion uses a highly polar solvent in terms of solvent solubility, when the compound is coated on a positive C-type retardation layer, the vertical alignment of the positive C-type retardation layer is further disturbed, which in turn causes a disturbance in the alignment of the photoalignable component, and thus reduces the alignment property of the positive A-type retardation layer. As described above, in the retardation plate of the prior art in which the positive A-type retardation layer is directly laminated on the positive C-type retardation layer, the positive A-type retardation layer exhibiting reverse wavelength dispersion is likely to have poor alignment or poor heat and light resistance.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a retardation plate containing a positive C-type retardation layer and a positive A-type retardation layer located directly adjacent to the positive C-type retardation layer, in which the positive A-type retardation layer exhibiting reverse wavelength dispersion has good alignment and improved heat and light resistance, and an optical member and a display device using the retardation plate. [Means for solving the problem]

[0008] That is, the present disclosure includes the following aspects. [1] A retardation plate comprising a positive C-type retardation layer and a positive A-type retardation layer located directly adjacent to the positive C-type retardation layer and containing a cured product of a polymerizable liquid crystal composition, the positive C-type retardation layer contains a photoalignment component, the polymerizable liquid crystal compound contained in the positive A-type retardation layer exhibits reverse wavelength dispersion, A retardation plate that satisfies the following conditions (1), (2), and (3): Condition (1): The positive C-type retardation layer has a birefringence index Δn in the thickness direction at a wavelength of 550 nm of less than −0.080. Condition (2): A photoalignment component is present on the surface of the positive C-type retardation layer on the side not directly adjacent to the positive A-type retardation layer. Condition (3): The absolute value ΔRth of the change in out-of-plane retardation at a wavelength of 550 nm before and after a heat resistance test (heating at a temperature of 85° C. for 500 hours) of a laminate of the positive C-type retardation layer and the positive A-type retardation layer is 15 nm or less. [2] The retardation plate according to [1], wherein when the surface of the positive C-type retardation layer on the side not directly adjacent to the positive A-type retardation layer is analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), the peak area of ​​the largest secondary ion derived from the photoalignment group is 2.5% or less of the total ion amount. [3] The retardation plate according to [1] or [2], wherein when a region of the positive C-type retardation layer, from the interface on the positive A layer side to a 100 nm region on the positive C-type retardation layer side in the thickness direction, is analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), the peak area of ​​the largest secondary ion derived from the photoalignment group is 2.5% or less of the total ion amount. [4] An optical member comprising the retardation plate according to any one of the above [1] to [3] and a polarizing plate. [5] A display device comprising the retardation plate according to any one of [1] to [3] above, or an optical member containing the retardation plate and a polarizing plate. [Effects of the Invention]

[0009] The present disclosure has an effect of providing a retardation plate including a positive C-type retardation layer and a positive A-type retardation layer located directly adjacent to the positive C-type retardation layer, in which the positive A-type retardation layer exhibiting reverse wavelength dispersion has good alignment and improved heat and light resistance, as well as an optical member and a display device using the retardation plate. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a retardation plate according to the present disclosure. [Figure 2]1 is a schematic cross-sectional view illustrating an example of a retardation plate according to the present disclosure. [Figure 3] FIG. 1 is a schematic cross-sectional view illustrating an example of an optical member according to the present disclosure. [Figure 4] 1 is a schematic cross-sectional view showing an example of an organic EL display panel including a retardation plate according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments and examples of the present disclosure will be described with reference to the drawings. However, the present disclosure can be implemented in many different forms, and should not be construed as being limited to the description of the embodiments and examples exemplified below. Furthermore, to clarify the explanation, the drawings may schematically depict the width, thickness, shape, etc. of each part compared to the actual form, but these are merely examples and do not limit the interpretation of the present disclosure. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals, and detailed descriptions may be omitted as appropriate. Furthermore, for convenience of explanation, the terms "upper" and "lower" may be used in some cases, but the up-down direction may be reversed. "In this specification, when a certain component, such as a certain region, is said to be "on (or under)" another component, such as another component, or another region, unless otherwise specified, this includes not only the case where it is directly above (or directly below) the other component, but also the case where it is above (or below) the other component, i.e., the case where another component is included between the two components above (or below) the other component.

[0012] In the present disclosure, the alignment regulation force refers to the action of aligning the liquid crystal compound in the retardation layer in a specific direction. In the present disclosure, (meth)acrylic refers to either acrylic or methacrylic, and (meth)acrylate refers to either acrylate or methacrylate. Furthermore, in this specification, the terms "plate," "sheet," and "film" are not distinguished from one another solely on the basis of differences in name, and "film surface (plate surface, sheet surface)" refers to the surface that coincides with the planar direction of the target film-like (plate-like, sheet-like) member when the target film-like (plate-like, sheet-like) member is viewed overall and globally. In addition, in the present disclosure, the use of "to" indicating a numerical range means that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0013] In the present disclosure, "in-plane retardation at wavelength λ nm" may be expressed as "Re(λ)," and "out-of-plane (thickness direction) retardation at wavelength λ nm" may be expressed as "Rth(λ)." Unless otherwise specified, the wavelength λ is 550 nm. The in-plane retardation (Re) and the out-of-plane retardation (Rth) can be calculated from Nx, Ny, Nz and the thickness d (nm) of the retardation layer by the following formula. In-plane phase difference (Re)=(Nx-Ny)×d Out-of-plane phase difference (Rth)=((Nx+Ny) / 2-Nz)×d In the present disclosure, the in-plane retardation (Re) and out-of-plane retardation (Rth) of a retardation plate or retardation layer are values ​​measured at a wavelength λ using a retardation measurement device (RETS-100, manufactured by Otsuka Electronics Co., Ltd.). In this disclosure, the refractive indices Nx, Ny, and Nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) with a sodium lamp (λ = 589 nm) as the light source. Wavelength dependency can also be measured using a multi-wavelength Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.) in combination with an interference filter. Values ​​from the Polymer Handbook (John Wiley & Sons, Inc.) and catalogs for various optical films can also be used. Examples of average refractive index values ​​for major optical films are listed below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0014] In the present disclosure, a positive A-type retardation layer is a layer that satisfies the relationship Nx > Ny ≒ Nz, where Nx is the refractive index in the X-axis direction, which is the direction with the highest refractive index along the in-plane direction of the layer, Ny is the refractive index in the Y-axis direction perpendicular to the X-axis along the in-plane direction of the layer, and Nz is the refractive index in the thickness direction of the layer. Here, the symbol “≒” includes not only the case where both are exactly the same but also the case where both are substantially the same. “Substantially the same” means that (Ny - Nz) × d (where d is the thickness of the film) is included in “Ny ≒ Nz” even when it is -8 to 8 nm. (Ny - Nz) × d is preferably -5 to 5 nm. Further, in the present disclosure, a positive C-type retardation layer is a layer that satisfies the relationship Nx ≒ Ny < Nz. Here, the symbol “≒” includes not only the case where both are exactly the same but also the case where both are substantially the same. “Substantially the same” means that (Nx - Ny) × d (where d is the thickness of the film) is included in “Nx ≒ Ny” even when it is 0 to 3 nm. (Nx - Ny) × d is preferably 0 to 2 nm. Further, in the positive A-type retardation layer, since Ny ≒ Nz, from the above calculation formulas of the in-plane retardation and the out-of-plane retardation, The out-of-plane retardation Rth in the positive A-type retardation layer = the in-plane retardation Re in the positive A-type retardation layer / 2 can be estimated.

[0015] I. Retardation Plate The present disclosure is a retardation plate containing a positive C-type retardation layer and a positive A-type retardation layer containing a cured product of a polymerizable liquid crystal composition, which is directly adjacent to the positive C-type retardation layer, where the positive C-type retardation layer contains a photo-alignment component, the polymerizable liquid crystal compound contained in the positive A-type retardation layer exhibits inverse wavelength dispersion, and satisfies the following conditions (1), (2), and (3). Condition (1): The thickness-direction birefringence Δn of the positive C-type retardation layer at a wavelength of 550 nm is less than -0.080. Condition (2): A photoalignment component is present on the surface of the positive C-type retardation layer on the side not directly adjacent to the positive A-type retardation layer. Condition (3): The absolute value ΔRth of the change in out-of-plane retardation at a wavelength of 550 nm before and after a heat resistance test (heating at a temperature of 85° C. for 500 hours) of a laminate of the positive C-type retardation layer and the positive A-type retardation layer is 15 nm or less.

[0016] 1 and 2 are schematic cross-sectional views showing an example of a retardation plate according to the present disclosure. The retardation plate 10 shown in FIG. 1 includes a laminate of a positive C-type retardation layer 1 and a positive A-type retardation layer 2 located directly adjacent to the positive C-type retardation layer 1. The retardation plate according to the present disclosure may include a region in the positive C-type retardation layer 1 where the liquid crystalline component contained in the positive A-type retardation layer has permeated (hereinafter, may be referred to as a "permeation region") (not shown). Furthermore, the retardation plate may have a permeation region, and further, in the permeation region 3, the liquid crystalline component contained in the positive A-type retardation layer may be vertically aligned. The retardation plate of the present disclosure may further include a substrate. In the retardation plate 10 illustrated in Fig. 2, a substrate 4 includes a laminate of a positive C-type retardation layer 1 positioned adjacent to the substrate and a positive A-type retardation layer 2 positioned directly adjacent to the positive C-type retardation layer 1.

[0017] In one embodiment of the retardation plate 10 illustrated in FIG. 2, the substrate 4 and the positive C-type retardation layer 1 are directly laminated, but a means for exerting an alignment regulating force may be attached to the surface of the substrate 4 on the side of the positive C-type retardation layer 1. In one embodiment of the retardation plate, a substrate 4, an alignment film, and a positive C-type retardation layer 1 may be laminated in this order (not shown). In the retardation plate of the present disclosure, from the viewpoint of improving productivity, it is preferable that no alignment film is contained between the substrate and the positive C-type retardation layer, and it is preferable that a substrate is contained that is located directly adjacent to the positive C-type retardation layer. Furthermore, in the retardation plate of the present disclosure, since the thickness after production can be reduced, the substrate 1 may be peeled off after production, so that the retardation plate does not need to contain the substrate as shown in FIG.

[0018] Condition (1): The positive C-type retardation layer has a birefringence index Δn in the thickness direction at a wavelength of 550 nm of less than −0.080. The positive C-type retardation layer of the present disclosure contains a photoalignment component, and yet has a Δn of less than −0.080, and has high vertical alignment properties. The positive C-type retardation layer may have Δn of −0.100 or less, −0.110 or less, or −0.200 or less. The lower limit is not particularly limited, but may be −0.250.

[0019] The Δn of the positive C-type retardation layer is determined by preparing the following measurement sample and measuring the thickness direction retardation Rth and in-plane retardation Re at a wavelength of 550 nm using a retardation measurement device (RETS-100, manufactured by Otsuka Electronics Co., Ltd.). The positive C-type retardation layer and the positive A layer are transferred to adhesive glass, and if a substrate is laminated, the substrate is peeled off to prepare a measurement sample in the order of positive C-type retardation layer / positive A layer / adhesive glass. An optical adhesive (Panaclean PD-S1, 25 μm, acrylic adhesive, manufactured by Panac Corporation) is used as the adhesive. The measurement conditions for retardation measurement are as follows: (A1) First, turn on the RETS-100 light source and leave it for at least 60 minutes to stabilize it. Then, select the rotating analyzer method and the θ mode (a mode for measuring angular phase difference and calculating Rth). By selecting this θ mode, the stage becomes a tilting rotation stage. (A2) Next, enter the following measurement conditions into the RETS-100. (Measurement conditions) Retardation measurement range: Rotating analyzer method Measurement spot diameter: φ5mm Tilt angle range: -40° to 40° Tilt step: 10° Measurement wavelength range: 400nm to 800nm Average refractive index of the layer to be measured: The measurement sample is measured using an Abbe refractometer (manufactured by Atago Co., Ltd.) in accordance with JIS K7142 using sodium D line (589 nm) as a light source, and the measured value (average refractive index) is entered. Thickness: Enter the total thickness of the positive C-type retardation layer and the positive A-type retardation layer. (A3) Next, background data is obtained without placing a sample in the device, using the device as a closed system, and this is performed every time the light source is turned on. (A4) Then, the sample is placed on the stage inside the device and measured.

[0020] The thickness of the retardation layer was measured by using a scanning transmission electron microscope (STEM) (Hitachi High-Technologies Corporation, product name "S-4800") to photograph a cross section of the retardation layer with the detector set to "TE," the acceleration voltage set to "30 kV," and the emission current set to "10 μA." The thickness of the positive C-type retardation layer and the positive A-type retardation layer was measured at 10 points on the cross section image, and the arithmetic mean value of the thicknesses at those 10 points was used. The penetration region was observed as the area where both fragments derived from the components contained in the positive A-type retardation layer and fragment ions derived from the components contained in the positive C-type retardation layer were detected by TOF-SIMS, and was included in the thickness of the positive C-type retardation layer.

[0021] The out-of-plane retardation Rth of the positive C-type retardation layer is calculated from the thickness of the positive C-type retardation layer and the Rth and Re of the retardation plate according to the following formula. Out-of-plane retardation Rth (nm) of positive C-type retardation layer = out-of-plane retardation Rth (nm) of retardation plate - (in-plane retardation Re (nm) / 2) As described above, the out-of-plane retardation Rth of the positive A-type retardation layer can be estimated as = the in-plane retardation Re / 2 of the positive A-type retardation layer. Since the in-plane retardation of the positive C-type retardation layer is much smaller than that of the positive A-type retardation layer, the in-plane retardation of the retardation plate can be regarded as the in-plane retardation Re of the positive A-type retardation layer. Using the calculated out-of-plane retardation Rth of the positive C-type retardation layer, Δn of the positive C-type retardation layer is calculated according to the following formula. Δn = out-of-plane retardation Rth (nm) of positive C-type retardation layer / thickness of positive C-type retardation layer (nm)

[0022] Condition (2): A photoalignment component is present on the surface of the positive C-type retardation layer on the side not directly adjacent to the positive A-type retardation layer. In the positive C-type retardation layer of the present disclosure, a photo-alignment component for aligning the positive A-type retardation layer is present on a surface directly adjacent to the positive A-type retardation layer, and further, a photo-alignment component is present on a surface not directly adjacent to the positive A-type retardation layer. When the photosensitive photo-alignment component is locally present in large amounts on the surface directly adjacent to the positive A-type retardation layer, the optical properties are likely to fluctuate due to the influence of the photosensitive photo-alignment component upon light irradiation. However, in the positive C-type retardation layer of the present disclosure, the photo-alignment component is not localized on the surface directly adjacent to the positive A-type retardation layer, and therefore the optical properties are less susceptible to fluctuations upon light irradiation.

[0023] The surface of the positive C-type retardation layer, which is not directly adjacent to the positive A-type retardation layer, is analyzed for surface components using a time-of-flight secondary ion mass spectrometer (TOF-SIMS) (TOF.SIMS5 manufactured by IONTOF) to determine whether or not a photoalignment component is present. The measurement conditions are set as follows: Primary ion: Bi3 ++ Primary ion accelerating voltage: 25 kV Primary ion current value: 0.2 pA Measurement area: 300 μm x 300 μm (using a neutralization gun for charge correction) Number of scans: 64 scans The presence or absence of a photo-alignment component on the surface of the positive C-type retardation layer that is not directly adjacent to the positive A-type retardation layer is confirmed based on the presence or absence of fragments derived from the photo-alignment component.

[0024] Condition (3): The absolute value ΔRth of the change in out-of-plane retardation at a wavelength of 550 nm before and after a heat resistance test (heating at a temperature of 85° C. for 500 hours) of a laminate of the positive C-type retardation layer and the positive A-type retardation layer is 15 nm or less. In the laminate of the positive C-type retardation layer and the positive A-type retardation layer of the present disclosure, fluctuation of the out-of-plane retardation due to heat is suppressed. The absolute value ΔRth of the change in out-of-plane retardation at a wavelength of 550 nm before and after the heat resistance test is more preferably 10 nm or less. The smaller ΔRth is, the more preferable, and the lower limit is not particularly limited and may be 0 nm.

[0025] In the laminate of the positive C-type retardation layer and the positive A-type retardation layer of the present disclosure, the absolute value ΔRth of the change in out-of-plane retardation at a wavelength of 550 nm before and after the heat resistance test is calculated in the same manner as in the condition (1) above. A measurement sample of the positive C-type retardation layer / positive A-type retardation layer / adhesive-backed glass is prepared, the out-of-plane retardation Rth before the heat resistance test is measured, and further the out-of-plane retardation Rth after the heat resistance test is measured, and the absolute value Δ of the change in out-of-plane retardation Rth before and after the heat resistance test is calculated.

[0026] The retardation plate of the present disclosure is a retardation plate containing a positive C-type retardation layer and a positive A-type retardation layer located directly adjacent to the positive C-type retardation layer and containing a cured product of a polymerizable liquid crystal composition, wherein the positive C-type retardation layer contains a photo-alignable component, and the polymerizable liquid crystal compound contained in the positive A-type retardation layer exhibits reverse wavelength dispersion, and satisfies the conditions (1), (2), and (3), thereby providing a retardation plate in which the positive A-type retardation layer exhibiting reverse wavelength dispersion has good alignment and improved heat and light resistance. As described above, in a conventional retardation plate in which a positive A-type retardation layer exhibiting reverse wavelength dispersion is directly laminated on the positive C-type retardation layer, the positive A-type retardation layer exhibiting reverse wavelength dispersion is likely to have poor alignment or poor heat and light resistance. In contrast, according to the present disclosure, even if the positive C-type retardation layer contains a photo-alignable component, the positive C-type retardation layer is controlled to have high vertical alignment so as to satisfy the condition (1). As a result, even if a reverse wavelength dispersion liquid crystal composition is directly coated on the positive C-type retardation layer to form a positive A-type retardation layer located directly adjacent to the positive C-type retardation layer, the vertical alignment of the positive C-type retardation layer is unlikely to be disturbed, and fluctuations of the photo-alignable component are also suppressed, thereby improving the alignment of the positive A-type retardation layer exhibiting reverse wavelength dispersion. Furthermore, since the photo-alignable component is not locally biased due to the condition (2), photodegradation of optical properties is easily suppressed. Furthermore, since the heat resistance is controlled so as to satisfy the condition (3), a retardation plate with improved heat and light resistance is obtained.

[0027] In the present disclosure, the method for enhancing the vertical alignment property of the positive C-type retardation layer so as to satisfy the conditions (1) and (3) is not particularly limited, and examples thereof include a method for achieving both improved vertical alignment property and curability by controlling the temperature in two or more stages when forming the positive C-type retardation layer; and a method for controlling the amount of a curing agent contained in a composition for the positive C-type retardation layer so as to cure the composition so as to enhance the vertical alignment.

[0028] In addition, the retardation plate of the present disclosure has a positive C-type retardation layer and a positive A-type retardation layer directly laminated together, and does not require an adhesive layer for bonding as in the past, so that the thickness can be reduced. The components included in the retardation plate will be described in detail below.

[0029] 1. Positive C-type retardation layer The positive C-type retardation layer 1 of the present disclosure is a layer that exhibits vertical alignment (homeotropic alignment), but is also capable of aligning liquid crystals horizontally because it is directly laminated on the positive A-type retardation layer 2. The positive C-type retardation layer 1 of the present disclosure may contain a vertically aligned liquid crystal component and a photoalignable component.

[0030] The positive C-type retardation layer 1 of the present disclosure may be a cured product of a thermosetting liquid crystal composition containing a vertically aligning liquid crystal component, a photoalignable component, and a thermal crosslinking agent, because it is easy to satisfy the conditions (1), (2), and (3). When the positive C-type retardation layer 1 is a cured product of a thermosetting liquid crystal composition containing a vertically aligning liquid crystal component, a photoalignment component, and a thermal crosslinking agent, the crosslinked structure improves the film's heat resistance and solvent resistance, resulting in high durability. When the positive C-type retardation layer 1 is a cured product of a thermosetting liquid crystal composition containing a vertically aligning liquid crystal component, a photoalignment component, and a thermal crosslinking agent, it is less likely to harden and more flexible than a cured product of a photocurable resin composition containing a polymerizable liquid crystal compound. This makes it easier to control the curing property while improving the vertical alignment property of the positive C-type retardation layer. Therefore, it is easy to improve the vertical alignment property of the positive C-type retardation layer while improving its heat resistance and solvent resistance. Meanwhile, on the surface side of the positive C-type retardation layer, the photoalignment component further imparts the function of an alignment layer to the cured film by irradiating it with polarized light, thereby functioning as both an alignment layer and a retardation layer. Since the photoalignment component is not locally concentrated on one surface of the positive C-type retardation layer, photodegradation of the optical properties is suppressed. Furthermore, when the positive C-type retardation layer 1 is a cured product of a thermosetting liquid crystal composition containing a vertically aligning liquid crystalline component, a photoalignable component, and a thermal crosslinking agent, the retardation plate of the present disclosure has a positive C-type retardation layer and a positive A-type retardation layer directly laminated with good adhesion, and can be made thin. In addition, since the positive C-type retardation layer has flexibility, the retardation plate can have good bending resistance.

[0031] 1-1. Liquid crystal component As the vertically oriented liquid crystal component, it is preferable to use a side-chain liquid crystal polymer having a liquid crystal constituent unit containing a liquid crystal moiety in the side chain, because this tends to provide good vertical alignment even when mixed with a photo-alignable component and also tends to impart flexibility.

[0032] The side-chain liquid-crystalline polymer (A) used in the present disclosure has a liquid-crystalline constituent unit containing a liquid-crystalline moiety in the side chain, and may further have a non-liquid-crystalline constituent unit containing an alkylene group in the side chain. The side-chain liquid-crystalline polymer (A) has a liquid-crystalline constituent unit containing a liquid-crystalline moiety in the side chain, and may further have a non-liquid-crystalline constituent unit containing an alkylene group in the side chain. Each of the structural units in the side chain liquid crystal polymer (A) will be explained below.

[0033] (1) Liquid Crystalline Constitutional Unit In an embodiment of the present disclosure, the liquid crystalline structural unit has a side chain containing a liquid crystalline moiety, i.e., a moiety exhibiting liquid crystallinity. The liquid crystalline structural unit is preferably a structural unit containing a mesogen exhibiting liquid crystallinity in the side chain. The liquid crystalline structural unit is preferably a structural unit derived from a compound exhibiting liquid crystallinity in which a polymerizable group is bonded to a mesogenic group via a spacer. In the present disclosure, the term "mesogen" refers to a highly rigid moiety exhibiting liquid crystallinity, such as a partial structure having two or more ring structures, preferably three or more ring structures, in which the ring structures are directly bonded to each other or the ring structures are connected via one to three atoms. By having such a moiety exhibiting liquid crystallinity in the side chain, the liquid crystalline structural unit is more likely to be vertically aligned. The ring structure may be an aromatic ring such as benzene, naphthalene, or anthracene, or may be a cyclic aliphatic hydrocarbon such as cyclopentyl or cyclohexyl. Furthermore, when the ring structures are linked via 1 to 3 atoms, examples of the structure of the linking portion include -O-, -S-, -OC(=O)-, -C(=O)-O-, -OC(=O)-O-, -NR-C(=O)-, -C(=O)-NR-, -OC(=O)-NR-, -NR-C(=O)-O-, -NR-C(=O)-NR-, -O-NR-, and -NR-O- (R is a hydrogen atom or a hydrocarbon group). Among these, the mesogen is preferably a rod-shaped mesogen in which the ring structures are connected in a rod-like shape at the para position in the case of benzene or at the 2,6 position in the case of naphthalene.

[0034] Furthermore, when the liquid crystalline structural unit is a structural unit containing a mesogen exhibiting liquid crystallinity in its side chain, it is preferable that the terminal of the side chain of the structural unit is a polar group or has an alkyl group from the viewpoint of vertical alignment. Specific examples of such polar groups include -F, -Cl, -CN, -OCF3, -OCF2H, -NCO, -NCS, -NO2, -NHC(=O)-R', -C(=O)-OR', -OH, -SH, -CHO, -S03H, -NR'2, -R ” , or -OR ” (R' is a hydrogen atom or a hydrocarbon group, R ” is an alkyl group).

[0035] The liquid crystal structural unit has a side chain of -R 2 -(L 1 -Ar 1 ) a -R 3 (wherein R 2 is -(CH2) m - or -(C2H4O) m’ represents a group represented by the formula: L 1 represents a single bond or a linking group represented by -O-, -OCO-, or -COO-, and 1 represents an arylene group having 6 to 10 carbon atoms which may have a substituent, and 1 and Ar 1 may be the same or different. 3 -F, -Cl, -CN, -OCF3, -OCF2H, -NCO, -NCS, -NO2, -NHCO-R 4 , -CO-OR 4 , -OH, -SH, -CHO, -SO3H, -NR 4 2, -R 5 , or -OR 5 , R 4 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R 5 represents an alkyl group having 1 to 6 carbon atoms; a is an integer of 2 to 4, and m and m' are each independently an integer of 2 to 10.) are examples of structural units having these structures.

[0036] R 2In the formula, m and m' are each independently an integer of 2 to 10. In terms of vertical alignment, m and m' are preferably 2 to 8, and more preferably 2 to 6.

[0037] Ar 1 In the formula (I), examples of the arylene group having 6 to 10 carbon atoms which may have a substituent include a phenylene group and a naphthylene group, and among these, a phenylene group is more preferred. 3 Examples of the substituent other than the above include an alkyl group having 1 to 5 carbon atoms, and halogen atoms such as a fluorine atom, a chlorine atom, and a bromine atom.

[0038] R 3 In R 4 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 3 In R 5 is an alkyl group having 1 to 6 carbon atoms, and is preferably an alkyl group having 1 to 5 carbon atoms.

[0039] The liquid crystal structural unit is preferably a structural unit derived from a monomer having a polymerizable ethylenic double bond-containing group. Examples of such a monomer having an ethylenic double bond-containing group include derivatives of (meth)acrylic acid ester, styrene, (meth)acrylamide, maleimide, vinyl ether, or vinyl ester. In particular, the liquid crystal structural unit is preferably a structural unit derived from a (meth)acrylic acid ester derivative in terms of vertical alignment.

[0040] In the embodiments of the present disclosure, the liquid crystal constitutional unit preferably contains a constitutional unit represented by the following general formula (I) in terms of vertical alignment.

[0041] [ka] (In general formula (I), R 1 represents a hydrogen atom or a methyl group, R 2is -(CH2) m - or -(C2H4O) m’ represents a group represented by the formula: L 1 represents a single bond or a linking group represented by -O-, -OCO-, or -COO-, and 1 represents an arylene group having 6 to 10 carbon atoms which may have a substituent, and 1 and Ar 1 may be the same or different. 3 -F, -Cl, -CN, -OCF3, -OCF2H, -NCO, -NCS, -NO2, -NHCO-R 4 , -CO-OR 4 , -OH, -SH, -CHO, -SO3H, -NR 4 2, -R 5 , or -OR 5 , R 4 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R 5 represents an alkyl group having 1 to 6 carbon atoms; a is an integer of 2 to 4, and m and m' are each independently an integer of 2 to 10.

[0042] In the structural unit represented by general formula (I), -R 2 -(L 1 -Ar 1 ) a -R 3 The group represented by may be the same as above.

[0043] Suitable specific examples of the liquid crystalline structural unit represented by general formula (I) include, but are not limited to, those represented by the following general formulae (I-1), (I-2) and (I-3).

[0044] [ka]

[0045] In the constitutional units represented by the above general formulas (I-1) to (I-3), R 2 , and R 3 are R in general formula (I), respectively. 2 , and R3 is the same as:

[0046] In the embodiments of the present disclosure, the liquid crystal structural unit may be used alone or in combination of two or more.

[0047] The copolymer can be synthesized using a monomer such as a (meth)acrylic acid ester derivative that induces a liquid crystalline structural unit. The monomer such as a (meth)acrylic acid ester derivative that induces a liquid crystalline structural unit can be used alone or in combination of two or more.

[0048] The content of the liquid crystalline structural units in the copolymer may be 100 mol%, assuming that the amount of structural units contained in the entire copolymer is 100 mol%, in order to improve the vertical alignment of the liquid crystalline structural units and to provide sufficient liquid crystal alignment. However, it is preferably set within the range of 40 mol% to 90 mol%, more preferably within the range of 40 mol% to 80 mol%, even more preferably within the range of 45 mol% to 70 mol%, and particularly preferably within the range of 50 mol% to 65 mol%. The content ratio of each structural unit in the copolymer is as follows: 1 It can be calculated from the integral value obtained by H-NMR measurement.

[0049] (2) Non-liquid crystal structural unit containing an alkylene group in the side chain The non-liquid crystal structural unit containing an alkylene group in the side chain has the effect of promoting vertical alignment of the liquid crystal moiety (mesogen) of the side chain of the liquid crystal structural unit when the side chain liquid crystal polymer is in a liquid crystal state. When the non-liquid crystal structural unit containing an alkylene group in the side chain is included, the vertical alignment property of the side chain liquid crystal polymer (A) is improved, and the solvent solubility is also improved. The non-liquid crystal structural unit containing an alkylene group in the side chain may have -L 2 -R 13 , or -L 2’ -R 14 (wherein L 2 Ha-(CH2) n - represents L 2’Ha-(C2H4O) n’ represents a linking group represented by -, and R 13 represents a methyl group which may have a substituent, an aryl group which may have an alkyl group, or -OR 15 represents R 14 and R 15 each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and n and n′ each independently represents an integer of 1 to 18.

[0050] L 2 Ha-(CH2) n - represents L 2’ Ha-(C2H4O) n’ Among them, -(CH2) is preferred because it tends to provide good vertical alignment. n - is preferred. Furthermore, n is an integer of 1 to 18, and preferably an integer of 2 to 18. 13 When n is a methyl group having a substituent or an alkyl group having a substituent, n is preferably an integer of 1. Furthermore, n' is an integer of 1 to 18, preferably an integer of 1 to 8, and more preferably an integer of 2 to 8.

[0051] R 14 and R 15 The alkyl group in may be straight-chain, branched, or cyclic, but is preferably straight-chain. R 14 , and R 15The alkyl group in is preferably an alkyl group having 1 to 20 carbon atoms, and specific examples thereof include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, and n-decyl groups, branched alkyl groups such as i-propyl, i-butyl, and t-butyl groups, alkenyl groups such as 1-propenyl and 1-butenyl groups, alkynyl groups such as ethynyl and 2-propynyl groups, cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, norbornyl, and adamantyl groups, and cycloalkenyl groups such as 1-cyclohexenyl groups. In the case of the above cycloalkyl groups, it is preferable that the linear alkyl group is substituted with a cycloalkyl group.

[0052] R 14 and R 15 The alkyl group in is not particularly limited, but is preferably an alkyl group having 1 to 12 carbon atoms in terms of in-plane uniformity of retardation.

[0053] R 13 , R 14 , and R 15 The aryl group in is preferably an aryl group having 6 to 20 carbon atoms, and specific examples thereof include a phenyl group, a naphthyl group, and an anthracenyl group, and among these, a phenyl group or a naphthyl group is preferred, and a phenyl group is more preferred. In the case of the above aryl group, it is preferably an aryl group substituted with a linear alkyl group.

[0054] The non-liquid crystal structural unit containing an alkylene group in the side chain may have, as a substituent, a reactive group that reacts with other components, and may have, for example, a thermally crosslinkable group similar to that of the copolymer (B) described later. Examples of the non-liquid crystal structural unit containing an alkylene group in a side chain include a non-liquid crystal, non-crosslinkable structural unit and a non-liquid crystal, thermally crosslinkable structural unit. The non-liquid crystal structural unit containing an alkylene group in a side chain may contain only non-liquid crystal, non-crosslinkable structural units, or may contain only non-liquid crystal, thermally crosslinkable structural units. The non-liquid crystalline structural unit containing an alkylene group in the side chain preferably contains at least a non-liquid crystalline non-crosslinkable structural unit, since this tends to result in good vertical alignment, and more preferably contains a non-liquid crystalline non-crosslinkable structural unit and a non-liquid crystalline thermally crosslinkable structural unit, since this tends to result in good vertical alignment and improved durability.

[0055] In the non-liquid crystalline and non-crosslinkable structural unit containing an alkylene group in the side chain, R 13 The substituents that the methyl group in 14 and R 15 Examples of the substituent that the alkyl group in the formula (I) may have include non-crosslinkable substituents, such as halogen atoms such as fluorine atom, chlorine atom and bromine atom, alkoxy groups, nitro groups, etc. Among these, halogen atoms such as fluorine atom, chlorine atom and bromine atom are preferred.

[0056] In the non-liquid crystal and non-crosslinkable structural unit containing an alkylene group in the side chain, R 13 , R 14 , and R 15 Examples of the substituent that the aryl group in (I) may have include non-crosslinkable substituents, such as halogen atoms (e.g., fluorine, chlorine, and bromine), alkyl groups, alkoxy groups, and nitro groups. Examples of the alkyl group include alkyl groups having 1 to 12 carbon atoms, such as alkyl groups having 1 to 9 carbon atoms. These alkyl groups may be linear or may have a branched or cyclic structure. Among these, halogen atoms (e.g., fluorine, chlorine, and bromine) and alkyl groups having 1 to 9 carbon atoms are preferred. Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclopentyl, cyclohexyl, cyclohexylmethyl, cyclohexylethyl, and cyclohexylpropyl groups. Hydrogen atoms in the alkyl group may be substituted with halogen atoms.

[0057] In the non-liquid crystalline and thermally crosslinkable structural unit containing an alkylene group in the side chain, R 13The methyl group, R 14 and R 15 The alkyl group in 13 , R 14 , and R 15 The substituent that the aryl group in (R) may have is preferably a thermally crosslinkable group, and examples thereof include the same thermally crosslinkable groups as those in the copolymer (B) described below, and may be, for example, at least one selected from the group consisting of a hydroxy group, a carboxy group, a mercapto group, a glycidyl group, an amino group, an amide group, a hydroxymethyl group, an alkoxymethyl group, a trialkoxysilyl group, a blocked isocyanate group, and an alkoxy group substituted with a methyl group. The hydroxymethyl group and the alkoxymethyl group, which are self-crosslinking groups, are represented by R 13 The methyl group in the formula (I) may be substituted with a hydroxy group or an alkoxy group to form a hydroxymethyl group or an alkoxymethyl group. Among the thermally crosslinkable groups, from the viewpoint of reactivity, a hydroxy group is preferred, and a primary hydroxy group is more preferred. Note that a primary hydroxy group refers to a hydroxy group in which the carbon atom to which the hydroxy group is bonded is a primary carbon atom.

[0058] The non-liquid crystal structural unit is preferably a structural unit derived from a monomer having a polymerizable ethylenic double bond-containing group. Examples of such a monomer having an ethylenic double bond-containing group include derivatives of (meth)acrylic acid ester, styrene, (meth)acrylamide, maleimide, vinyl ether, or vinyl ester. From the viewpoint of vertical alignment, the non-liquid crystal structural unit is preferably a structural unit derived from a (meth)acrylic acid ester derivative or styrene, and more preferably a structural unit derived from a (meth)acrylic acid ester derivative.

[0059] In an embodiment of the present disclosure, the non-liquid crystal structural unit preferably has a structural unit represented by the following formula (II):

[0060] [ka] (In general formula (II), R 11 represents a hydrogen atom or a methyl group, and R 12 -L 2 -R 13 , or -L 2’ -R 14 L represents a group represented by 2 Ha-(CH2) n - represents L 2’ Ha-(C2H4O) n’ represents a linking group represented by -, and R 13 represents a methyl group which may have a substituent, an aryl group which may have an alkyl group, or -OR 15 represents R 14 and R 15 each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and n and n' each independently represents an integer of 1 to 18.

[0061] In the constitutional unit represented by formula (II), -L 2 -R 13 , or -L 2’ -R 14 The group represented by may be the same as above.

[0062] In an embodiment of the present disclosure, when the non-liquid crystal structural unit is a non-liquid crystal and non-crosslinkable structural unit, examples of the optional substituent contained in the structural unit represented by formula (II) include the aforementioned non-crosslinkable substituents. Furthermore, in the embodiment of the present disclosure, when the non-liquid crystal structural unit is a non-liquid crystal and thermally crosslinkable structural unit, examples of the optional substituent contained in the structural unit represented by formula (II) include the above-mentioned thermally crosslinkable group. One non-liquid crystal and thermally crosslinkable structural unit preferably has one thermally crosslinkable group, but may have two or more thermally crosslinkable groups.

[0063] In an embodiment of the present disclosure, when the non-liquid crystalline constituent unit includes a non-liquid crystalline and thermally crosslinkable constituent unit, it is preferable that the non-liquid crystalline constituent unit include a constituent unit represented by the following formula (III) from the viewpoint of improving reactivity and durability.

[0064] [ka] (In the above formula (III), Z a represents at least one monomer unit selected from the group consisting of the following formulae (a-1) to (a-6), and R 16 is a linear alkylene group having 1 to 11 carbon atoms which may have -O- in the carbon chain, and Y a represents a thermally crosslinkable group.

[0065] [ka] (In the above formulas (a-1) to (a-6), R 11 represents a hydrogen atom, a methyl group, a chlorine atom, or a phenyl group, and R 17 represents a hydrogen atom or a methyl group, and R 18 is a hydrogen atom, a methyl group, a chlorine atom, or a phenyl group, R 19 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and L a represents a single bond, -O-, -S-, -COO-, -COS-, -CO-, or -OCO-; L a is a single bond, R 16 is directly bonded to the styrene backbone.)

[0066] R 16 is a linear alkylene group having 1 to 11 carbon atoms which may have -O- in the carbon chain, but -(CH2) n” -or-(C2H4O) m”Preferably it is -C2H4- (n" is 1 to 11, m" is 1 to 4), preferably n" is 2 to 11 and m" is 1 to 4, and more preferably n" is 4 to 11 and m" is 2 to 4. If n" and m" are too small, the distance between the thermally crosslinkable group and the main skeleton of the copolymer in the thermally crosslinkable constituent unit will be short, making it difficult for the thermal crosslinking agent to bond to the thermally crosslinkable group and potentially reducing the reactivity between the thermally crosslinkable constituent unit and the thermal crosslinking agent. On the other hand, if n" and m" are too large, the chain length of the linking group in the thermally crosslinkable constituent unit will be long, making it difficult for the terminal thermally crosslinkable group to be exposed to the surface and making it difficult for the thermal crosslinking agent to bond to the thermally crosslinkable group, potentially reducing the reactivity between the thermally crosslinkable constituent unit and the thermal crosslinking agent. Y a The thermally crosslinkable group may be the same as the thermally crosslinkable group described above, and may be, for example, at least one selected from the group consisting of a hydroxy group, a carboxy group, a mercapto group, a glycidyl group, an amino group, an amide group, a hydroxymethyl group, an alkoxymethyl group, a trialkoxysilyl group, a blocked isocyanate group, and an alkoxy group substituted with a methyl group. The hydroxymethyl group and the alkoxymethyl group, which are self-crosslinking groups, are substituted with a methyl group (R 16 The methylene group in the formula (I) may be substituted with a hydroxy group or an alkoxy group to form a hydroxymethyl group or an alkoxymethyl group.

[0067] Furthermore, in an embodiment of the present disclosure, when the non-liquid crystal structural unit includes a non-liquid crystal and thermally crosslinkable structural unit, the non-liquid crystal and thermally crosslinkable structural unit may be the same as the structural unit represented by formula (III) described below in the side chain liquid crystal polymer (A) of the second present disclosure described below.

[0068] The copolymer may have one or more types of non-liquid crystal structural units. Of the constituent units represented by general formula (II), examples of non-liquid crystal and non-crosslinkable constituent units include those represented by the following chemical formulae (II-1) to (II-10). Among the constituent units represented by general formula (II), examples of non-liquid crystal and thermally crosslinkable constituent units include structures in which one hydrogen atom of a hydrocarbon group of the following chemical formulas (II-1) to (II-10) is substituted with the thermally crosslinkable group.Furthermore, examples of non-liquid crystal and thermally crosslinkable constituent units include the following chemical formulas (III-1) to (III-11).

[0069] [ka]

[0070] [ka]

[0071] In addition, structural units represented by chemical formulas (III-1) to (III-12) described in paragraph 0294 of WO 2022 / 158555 can also be used.

[0072] The copolymer can be synthesized using a monomer such as a (meth)acrylic acid ester derivative that derives the non-liquid crystal structural unit. The monomer such as a (meth)acrylic acid ester derivative that derives the non-liquid crystal structural unit can be used alone or in combination of two or more.

[0073] In order to improve the vertical alignment of the liquid crystalline structural units and to provide sufficient liquid crystal alignment, the content of the non-liquid crystal structural units in the copolymer is preferably set within the range of 10 mol% to 60 mol%, more preferably within the range of 15 mol% to 50 mol%, even more preferably within the range of 15 mol% to 45 mol%, and particularly preferably within the range of 20 mol% to 40 mol%, when the amount of structural units contained in the entire copolymer is taken as 100 mol%.

[0074] When the copolymer contains both a non-liquid crystal, non-crosslinkable constituent unit and a non-liquid crystal, thermally crosslinkable constituent unit as the non-liquid crystal constituent unit, the content of the non-liquid crystal, thermally crosslinkable constituent unit is preferably set in the range of 10 mol % to 70 mol %, and more preferably set in the range of 30 mol % to 50 mol %, when the total amount of the non-liquid crystal constituent units contained in the entire copolymer is taken as 100 mol %. The content ratio of each structural unit in the copolymer is as follows: 1 It can be calculated from the integral value obtained by H-NMR measurement.

[0075] (3) Other constituent units The side chain liquid crystal polymer (A) used in the present disclosure may further have other structural units. Examples of other structural units include thermally crosslinkable structural units that do not contain an alkylene group in the side chain but have the thermally crosslinkable group. Examples of the thermally crosslinkable constituent unit that does not contain an alkylene group in the side chain but has the thermally crosslinkable group include (meth)acrylic acid, 4-hydroxystyrene, and 4-carboxystyrene. The side chain liquid crystal polymer (A) used in the present disclosure preferably has at least one type of thermally crosslinkable structural unit containing a thermally crosslinkable group in a side chain selected from the group consisting of non-liquid crystal and thermally crosslinkable structural units containing an alkylene group in a side chain and thermally crosslinkable structural units not containing an alkylene group in a side chain but having the thermally crosslinkable group, from the viewpoint of improving the durability and reliability of the retardation layer.

[0076] The content ratio of the above-mentioned other structural units in the copolymer is preferably set within the range of 30 mol % or less, and more preferably within the range of 20 mol % or less, when the amount of structural units contained in the entire copolymer is taken as 100 mol %, in order to improve the vertical alignment of the liquid crystalline structural units and to obtain sufficient liquid crystal alignment properties.

[0077] (4) Copolymer of side-chain liquid crystal polymer (A) In an embodiment of the present disclosure, the side-chain liquid crystal polymer (A) may be a block copolymer having a block portion composed of liquid crystalline structural units and a block portion composed of non-liquid crystalline structural units containing an alkylene group in the side chain, or may be a random copolymer in which the liquid crystalline structural units and the non-liquid crystalline structural units containing an alkylene group in the side chain are irregularly arranged. In this embodiment, a random copolymer is preferred from the viewpoint of improving the vertical alignment property and in-plane uniformity of the retardation value of the side-chain liquid crystal polymer.

[0078] The mass average molecular weight Mw of the side-chain liquid crystal polymer copolymer is not particularly limited, but is preferably in the range of 10,000 to 100,000, more preferably in the range of 30,000 to 90,000, and even more preferably in the range of 40,000 to 80,000. By having it in the above range, the vertical alignment property of the side-chain liquid crystal polymer and the liquid crystal alignment performance of the positive C-type retardation layer are excellent.

[0079] The mass average molecular weight Mw is a polystyrene-equivalent value measured by GPC (gel permeation chromatography).

[0080] A method for synthesizing a copolymer of the side chain liquid crystal polymer (A) includes a method of copolymerizing a monomer that derives a liquid crystalline structural unit and a monomer that derives a non-liquid crystalline structural unit containing an alkylene group in the side chain by a conventionally known production method. The side chain liquid crystal polymer (A) may be used in the form of a solution obtained when the copolymer is synthesized, or in the form of a powder, or in the form of a solution obtained by redissolving the purified powder in a solvent described below.

[0081] The side-chain liquid crystal polymer (A) may be used alone or in combination of two or more. In this embodiment, in order to exhibit vertical alignment properties, the content of the side-chain liquid crystal polymer is preferably 20 to 80 parts by mass, more preferably 25 to 70 parts by mass, and even more preferably 30 to 60 parts by mass, per 100 parts by mass of the solid content of the liquid crystal composition. In the present disclosure, the solid content refers to all components excluding the solvent, and for example, even if a polymerizable liquid crystal compound described below is in a liquid state, it is included in the solid content.

[0082] 1-2. Photo-orientable components Examples of the photo-alignable component used in the positive C-type retardation layer include a compound containing a photo-alignable group, or a polymer having a photo-alignable structural unit containing a photo-alignable group in the side chain. The photo-alignable component may be a copolymer having a photo-alignable constituent unit containing a photo-alignable group in its side chain and a thermally crosslinkable constituent unit containing a thermally crosslinkable group in its side chain, or may be a compound having a photo-alignable group and a thermally crosslinkable group different from the copolymer.

[0083] As the photo-alignment component used in the positive C-type retardation layer, which is a cured product of a thermosetting liquid crystal composition containing a photo-alignment component and a thermal crosslinking agent, it is preferable to use a copolymer having a photo-alignment constituent unit containing a photo-alignment group in a side chain and a thermal crosslinking constituent unit containing a thermal crosslinking group in a side chain, in order to exhibit good vertical alignment properties and liquid crystal alignment ability. Among these, it is preferable to use a copolymer (B) (photo-orientable copolymer) having a photo-orientable structural unit containing a photo-orientable group in the side chain through a specific structure and a thermally crosslinkable structural unit containing a thermally crosslinkable group in the side chain.

[0084] (1) Photo-orientable structural unit The photoalignable structural unit of the present disclosure may have a structural unit represented by the following formula (1).

[0085] [ka] (In the above formula (1), Z 1 represents at least one monomer unit selected from the group consisting of the following formulas (1-1) to (1-6), X represents a photoalignment group, and L 11 represents a single bond, -O-, -S-, -COO-, -COS-, -CO-, -OCO-, or a combination of any of these with an arylene group.

[0086] [ka] (In the above formulas (1-1) to (1-6), R 21 represents a hydrogen atom, a methyl group, a chlorine atom, or a phenyl group, and R 22 represents a hydrogen atom or a methyl group, and R 23 is a hydrogen atom, a methyl group, a chlorine atom, or a phenyl group, R 24 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. )

[0087] The monomer unit constituting the photoalignable structural unit may be at least one selected from the group consisting of the above formulas (1-1) to (1-6). 1 is at least one selected from the group consisting of formula (1-2), -L 11 -X may be bonded to any of the ortho, meta, and para positions, but -L 11 It is preferable that -X is bonded to the para position, since the distance between the photoalignable groups tends to be small and photoalignment is easily obtained. As the monomer unit constituting the photo-alignable structural unit, at least one selected from the group consisting of formulas (1-1) and (1-2) is preferred from the viewpoint of ease of raw material procurement. Furthermore, when at least one selected from the group consisting of formula (1-2) is used, the photo-alignable component such as copolymer (B) is more likely to become non-liquid crystal, and phase separation from the liquid crystalline component such as the side chain liquid crystalline polymer (A) is more likely to occur, improving the vertical alignment of the liquid crystalline component such as side chain liquid crystalline polymer (A). In addition, the rigidity of the photo-alignable structural unit of the photo-alignable component such as copolymer (B) is increased, making it easier to reduce the distance between photo-alignable groups, and thus making it easier to obtain excellent photo-alignment. This is more preferred.

[0088] Furthermore, when the copolymer has a styrene skeleton and contains a large number of π electron systems, it is considered that the positive C-type retardation layer formed using the copolymer also has high adhesion to a liquid crystalline material that is directly laminated on the positive C-type retardation layer to which this alignment ability has been imparted, due to the interaction of the π electron systems.

[0089] L11 represents a single bond, -O-, -S-, -COO-, -COS-, -CO-, -OCO-, or a combination of these with an arylene group, and links the monomer unit with the photo-alignable group X. When the photo-alignable constituent unit of the copolymer (B) used in the present disclosure does not have a linear alkylene group between the photo-alignable group and the monomer unit, the photo-alignable component such as the copolymer (B) used in the present disclosure tends to become non-liquid crystal, as described above, and the compatibility with the liquid crystal component such as the side chain liquid crystal polymer (A) decreases, making it more likely to phase separate from the liquid crystal component such as the side chain liquid crystal polymer (A), and the rigidity increases, making it more likely that the distance between the photo-alignable groups decreases, resulting in excellent photo-alignment properties.

[0090] The above L 11 is a single bond, the photo-orientable group X is a monomer unit Z 1 Specific examples of the divalent linking group include -O-, -S-, -COO-, -COS-, -CO-, -OCO-, -C6H4-, -C6H4O-, -OCOC6H4O-, -COOC6H4O-, and -OC6H4O-, where -C6H4- is a phenylene group.

[0091] On the other hand, the photoalignable group is a functional group that exhibits anisotropy by undergoing a photoreaction upon irradiation with light, and is preferably a functional group that undergoes a photodimerization reaction or a photoisomerization reaction.

[0092] Examples of photoalignable groups that cause a photodimerization reaction include cinnamoyl groups, chalcone groups, coumarin groups, anthracene groups, quinoline groups, azobenzene groups, and stilbene groups. The benzene ring in these functional groups may have a substituent, which may be any group that does not interfere with the photodimerization reaction, such as an alkyl group, an aryl group, a cycloalkyl group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, a trifluoromethyl group, or a cyano group.

[0093] The photo-alignable group that undergoes a photoisomerization reaction is preferably one that undergoes a cis-trans isomerization reaction, and examples thereof include a cinnamoyl group, a chalcone group, an azobenzene group, and a stilbene group. The benzene ring in these functional groups may have a substituent. The substituent may be any one that does not interfere with the photoisomerization reaction, and examples thereof include an alkoxy group, an alkyl group, a halogen atom, a trifluoromethyl group, and a cyano group.

[0094] Among these, the photoalignable group is preferably a cinnamoyl group. Specifically, the cinnamoyl group is preferably at least one selected from the group consisting of groups represented by the following formulae (x-1) and (x-2):

[0095] [ka]

[0096] In the above formula (x-1), R 31 represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, or a cycloalkyl group having 1 to 18 carbon atoms. However, the alkyl group, aryl group, and cycloalkyl group may be bonded via an ether bond, ester bond, amide bond, or urea bond, and may have a substituent. R 32 ~R 35 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, a cycloalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a cyano group. However, the alkyl group, aryl group, and cycloalkyl group may be bonded via an ether bond, an ester bond, an amide bond, or a urea bond, and may have a substituent. 36 and R 37 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, or an alkoxy group having 1 to 18 carbon atoms. In addition, in the above formula (x-2), R 41 ~R 45R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, a cycloalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a cyano group. However, the alkyl group, aryl group, and cycloalkyl group may be bonded via an ether bond, an ester bond, an amide bond, or a urea bond, and may have a substituent. 46 and R 47 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, or an alkoxy group having 1 to 18 carbon atoms.

[0097] In addition, when the photo-alignable group is a cinnamoyl group represented by the above formula (x-1), the benzene ring of the styrene skeleton (formula (1-2)) contained in the monomer unit may be the benzene ring of the cinnamoyl group.

[0098] Furthermore, the cinnamoyl group represented by the above formula (x-1) is more preferably a group represented by the following formula (x-3).

[0099] [ka]

[0100] In the above formula (x-3), R 32 ~R 37 is the same as the above formula (x-1). 38 represents a hydrogen atom, an alkoxy group having 1 to 18 carbon atoms, a cyano group, an alkyl group having 1 to 18 carbon atoms, a phenyl group, a biphenyl group, or a cyclohexyl group. However, the alkyl group, phenyl group, biphenyl group, and cyclohexyl group may be bonded via an ether bond, an ester bond, an amide bond, or a urea bond. n represents an integer of 1 to 5, and R 38 may be bonded to any of the ortho, meta, and para positions. When n is 2 to 5, R 38 may be the same or different. Among them, n is 1 and R 38 is preferably attached at the para position.

[0101] The copolymer may have one or more types of photoalignable structural units. The copolymer can be synthesized using a monomer having a photoalignment group that induces the photoalignment structural unit. The monomer having a photoalignment group can be used alone or in combination of two or more.

[0102] The content of the photoalignable structural units in the copolymer can be set within a range of 10 mol% to 90 mol%, preferably within a range of 20 mol% to 80 mol%, when the amount of structural units contained in the entire copolymer is taken as 100 mol%. If the content of the photoalignable structural units is low, sensitivity may decrease, making it difficult to impart good liquid crystal alignment ability. On the other hand, if the content of the photoalignable structural units is high, the content of the thermally crosslinkable structural units may be relatively low, resulting in insufficient thermosetting properties and making it difficult to maintain good liquid crystal alignment ability.

[0103] (2) Thermally crosslinkable structural unit The thermally crosslinkable constituent unit in the present disclosure is a moiety that bonds with a thermal crosslinking agent upon heating. The thermally crosslinkable structural unit may be a structural unit having a thermally crosslinkable group. The thermally crosslinkable group may be a group that crosslinks when heated at, for example, 30°C to 250°C, and examples thereof include a hydroxy group, a carboxy group, a phenolic hydroxy group, a mercapto group, a glycidyl group, an amino group, and an amide group. Among these, from the viewpoint of reactivity, an aliphatic hydroxy group is preferred, and a primary hydroxy group is more preferred. Note that a primary hydroxy group refers to a hydroxy group in which the carbon atom to which the hydroxy group is bonded is a primary carbon atom. The thermally crosslinkable group may also be a self-crosslinkable group capable of crosslinking with the same crosslinking group. Examples of the self-crosslinking group include a hydroxymethyl group, an alkoxymethyl group, a trialkoxysilyl group, and a blocked isocyanate group. When the thermally crosslinkable structural unit has a self-crosslinking group, the thermally crosslinkable structural unit can also function as a thermal crosslinking agent, which is preferable because it is likely to improve photoalignment performance and solvent resistance.When the thermally crosslinkable structural unit has a self-crosslinking group, it is thought that it is likely to react with the thermally crosslinkable structural unit in the molecule. The thermally crosslinkable structural unit preferably contains at least one selected from the group consisting of a hydroxy group, a carboxy group, and a mercapto group, from the viewpoint of photoalignment performance and solvent resistance. Among these, the thermally crosslinkable structural unit preferably contains a structural unit having at least one type of thermally crosslinkable group selected from the group consisting of a hydroxy group, a carboxy group, and a mercapto group, and a structural unit having at least one type of self-crosslinking group selected from the group consisting of a hydroxymethyl group, an alkoxymethyl group, a trialkoxysilyl group, and a blocked isocyanate group, as this makes it easier to improve the photoalignment performance and solvent resistance. The alkoxymethyl group of the self-crosslinking group preferably has an alkoxy group with 1 to 6 carbon atoms, and specific examples include a methoxymethyl group, an ethoxymethyl group, various propoxymethyl groups, various butoxymethyl groups, various pentoxymethyl groups, etc. Among these, the alkoxymethyl group is more preferably one with an alkoxy group with 1 to 4 carbon atoms, and even more preferably one with 1 to 2 carbon atoms, and a methoxymethyl group or an ethoxymethyl group is preferred from the viewpoint of good crosslinkability.

[0104] Examples of the monomer units constituting the thermally crosslinkable structural unit include acrylic esters, methacrylic esters, styrene, acrylamide, methacrylamide, maleimide, vinyl ethers, and vinyl esters. The thermally crosslinkable constituent unit may be a constituent unit derived from acrylic acid or methacrylic acid when the thermally crosslinkable group is a carboxy group, or may be a constituent unit derived from vinyl alcohol when the thermally crosslinkable group is a hydroxy group.

[0105] An example of the thermally crosslinkable constitutional unit is a constitutional unit represented by the following formula (2).

[0106] [ka] (In the above formula (2), Z 2 represents at least one monomer unit selected from the group consisting of the following formulae (2-1) to (2-6), and R 50 represents a linear alkylene group having 1 to 11 carbon atoms which may have -O- in the carbon chain, and Y represents a thermally crosslinkable group.

[0107] [ka] (In the above formulas (2-1) to (2-6), R 51 represents a hydrogen atom, a methyl group, a chlorine atom, or a phenyl group, and R 52 represents a hydrogen atom or a methyl group, and R 53 is a hydrogen atom, a methyl group, a chlorine atom, or a phenyl group, R 54 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and L 12 represents a single bond, -O-, -S-, -COO-, -COS-, -CO-, or -OCO-; L 12 is a single bond, R 50 is directly bonded to the styrene backbone.)

[0108] In addition, Z 2 When at least one selected from the group consisting of formula (2-2), -L 12 -Y may be bonded to any of the ortho, meta, and para positions, but -L 12 It is preferable that -Y is bonded to the para position, since this provides excellent reactivity in thermal crosslinking.

[0109] Among them, from the viewpoint of ease of procurement of raw materials, at least one monomer unit selected from the group consisting of formulas (2-1) and (2-2) is preferred as the monomer unit constituting the thermally crosslinkable structural unit. Furthermore, at least one monomer unit selected from the group consisting of formula (2-2) is more preferred because it makes the copolymer (B) more non-liquid crystalline and facilitates phase separation from the side-chain liquid crystalline polymer (A), thereby improving the vertical alignment of the side-chain liquid crystalline polymer (A).

[0110] In the above formula (2), the thermally crosslinkable group for Y may be the same as above, or may be a self-crosslinkable group. In the above formula (2), the thermally crosslinkable group of Y may be at least one type of thermally crosslinkable group selected from the group consisting of a hydroxy group, a carboxy group, a mercapto group, a glycidyl group, an amino group, an amide group, a hydroxymethyl group, an alkoxymethyl group, a trialkoxysilyl group, a blocked isocyanate group, and an alkoxy group substituted with a methyl group, and may be at least one type of thermally crosslinkable group selected from the group consisting of a hydroxy group, a carboxy group, a mercapto group, a glycidyl group, an amino group, and an amide group. The hydroxymethyl group and the alkoxymethyl group, which are self-crosslinking groups, may be at least one type of thermally crosslinkable group selected from the group consisting of a methyl group (R 50 The methylene group in the formula (I) may be substituted with a hydroxy group or an alkoxy group to form a hydroxymethyl group or an alkoxymethyl group. From the viewpoint of reactivity, the thermally crosslinkable group for Y preferably contains an aliphatic hydroxy group, and more preferably contains a primary hydroxy group.

[0111] In the above formula (2), L 12 represents a single bond, -O-, -S-, -COO-, -COS-, -CO-, or -OCO-. 12 is a single bond, the thermal crosslinkable group Y is a monomer unit Z 2 is directly bonded to R 50 is a linear alkylene group having 1 to 11 carbon atoms which may have -O- in the carbon chain, but -(CH2) j -or-(C2H4O) kPreferably, it is -C2H4- (j is 1 to 11, k is 1 to 4), preferably j is 2 to 11 and k is 1 to 4, and more preferably j is 4 to 11 and k is 2 to 4. If j and k are too small, the distance between the thermally crosslinkable group and the main skeleton of the copolymer in the thermally crosslinkable constituent unit will be short, making it difficult for the thermal crosslinking agent to bond to the thermally crosslinkable group, and there is a risk of reducing the reactivity between the thermally crosslinkable constituent unit and the thermal crosslinking agent. On the other hand, if j and k are too large, the chain length of the linking group in the thermally crosslinkable constituent unit will be long, making it difficult for the terminal thermally crosslinkable group to be exposed to the surface, making it difficult for the thermal crosslinking agent to bond to the thermally crosslinkable group, and there is a risk of reducing the reactivity between the thermally crosslinkable constituent unit and the thermal crosslinking agent.

[0112] The copolymer may have one type of thermally crosslinkable constituent unit or two or more types of units. The copolymer can be synthesized using a monomer having a thermally crosslinkable group that derives the thermally crosslinkable structural unit. The monomer having a thermally crosslinkable group can be used alone or in combination of two or more types.

[0113] Examples of the monomer having a thermal crosslinkable group include, but are not limited to, the following: Examples of acrylic acid ester compounds and methacrylic acid ester compounds include monomers having a hydroxy group and an acrylic group or a methacrylic group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2,3-dihydroxypropyl acrylate, 2,3-dihydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, triethylene glycol monoacrylate, tetraethylene glycol monoacrylate, dipropylene glycol monoacrylate, tripropylene glycol monoacrylate, and tetrapropylene glycol monoacrylate. Examples of the styrene compound include monomers having a hydroxy group and a styrene group, such as an ester of 4-vinylbenzoic acid and a diol, an ester of 4-vinylbenzoic acid and diethylene glycol, an ether of hydroxystyrene and a diol, and an ether of hydroxystyrene and diethylene glycol. Other examples of monomers that can be used to form thermally crosslinkable structural units include those described in paragraphs 0075 to 0079 of Japanese Patent No. 5626493. Furthermore, the hydroxyl group in the above examples may be substituted with a carboxyl group or a glycidyl group.

[0114] Among the monomers having a thermal crosslinkable group, examples of monomers having a self-crosslinking group include acrylamide compounds or methacrylamide compounds substituted with a hydroxymethyl group or an alkoxymethyl group, such as N-hydroxymethylacrylamide, N-hydroxymethylmethacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-ethoxymethylacrylamide, N-ethoxymethylmethacrylamide, N-butoxymethylacrylamide, and N-butoxymethylmethacrylamide; monomers having a trialkoxysilyl group, such as 3-trimethoxysilylpropyl acrylate, 3-triethoxysilylpropyl acrylate, 3-trimethoxysilylpropyl methacrylate, and 3-triethoxysilylpropyl methacrylate; and monomers having a blocked isocyanate group, such as 2-(0-(1'-methylpropylideneamino)carboxyamino)ethyl methacrylate and 2-(3,5-dimethylpyrazolyl)carbonylaminoethyl methacrylate.

[0115] The content of the thermally crosslinkable structural units in the copolymer can be set within a range of 5 mol% to 90 mol%, preferably within a range of 20 mol% to 80 mol%, when the amount of structural units contained in the entire copolymer is taken as 100 mol%. If the content of the thermally crosslinkable structural units is low, sufficient thermosetting properties may not be obtained, making it difficult to maintain good liquid crystal alignment ability. Furthermore, if the content of the thermally crosslinkable structural units is high, the content of the photoalignable structural units will be relatively low, which may reduce sensitivity and make it difficult to impart good liquid crystal alignment ability.

[0116] (3) Other structural units In the present disclosure, the copolymer may contain, in addition to the photoalignable structural unit and the thermally crosslinkable structural unit, a structural unit that does not have either a photoalignable group or a thermally crosslinkable group. By including other structural units in the copolymer, for example, solvent solubility, heat resistance, reactivity, etc. can be improved.

[0117] Examples of monomer units constituting a structural unit having neither a photoalignable group nor a thermally crosslinkable group include acrylic acid esters, methacrylic acid esters, maleimides, acrylamides, acrylonitrile, maleic anhydride, styrene, vinyl, etc. Among these, acrylic acid esters, methacrylic acid esters, and styrene are preferred, as with the thermally crosslinkable structural unit.

[0118] Examples of monomers that form structural units that do not have such a photoalignment group or a thermal crosslinking group include acrylic acid ester compounds, methacrylic acid ester compounds, maleimide compounds, acrylamide compounds, acrylonitrile, maleic anhydride, styrene compounds, and vinyl compounds. Specifically, for example, among the monomers described in paragraphs 0036 to 0040 of WO 2010 / 150748, a monomer having neither a photoalignable group nor a thermally crosslinkable group can be used.

[0119] The copolymer may contain one or more types of structural units that do not have a photoalignable group or a thermally crosslinkable group.

[0120] The content of the structural units not having the photoalignable group and the thermally crosslinkable group in the copolymer is preferably in the range of 0 mol% to 50 mol%, and more preferably in the range of 0 mol% to 30 mol%, when the amount of structural units contained in the entire copolymer is taken as 100 mol%. If the content of the structural units is high, the content of the photoalignable structural units and the thermally crosslinkable structural units will be relatively low, which will reduce sensitivity and make it difficult to impart good liquid crystal alignment ability. In addition, sufficient thermosetting properties will not be obtained, making it difficult to maintain good liquid crystal alignment ability.

[0121] (4) Copolymer (B) The mass-average molecular weight of the copolymer (B) is not particularly limited and can be, for example, about 3,000 to 200,000, preferably in the range of 4,000 to 100,000. If the mass-average molecular weight is too large, the solubility in solvents may be reduced or the viscosity may be increased, which may reduce handleability and make it difficult to form a uniform film. On the other hand, if the mass-average molecular weight is too small, the copolymer may not be sufficiently cured during heat curing, which may reduce solvent resistance and heat resistance. The mass average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0122] The copolymer (B) can be synthesized by copolymerizing a monomer having a photoalignable group with a monomer having a thermally crosslinkable group by a conventionally known production method. The copolymer (B) may be used in the form of a solution obtained when the copolymer is synthesized, in the form of a powder, or in the form of a solution obtained by redissolving purified powder in a solvent described below.

[0123] The copolymer (B) may be used singly or in combination of two or more. In this embodiment, in order to exert alignment ability on the liquid crystal material to be directly laminated, the content of the copolymer (B) is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 10 to 30 parts by mass, per 100 parts by mass of the solid content of the positive C-type retardation composition.

[0124] 1-3. Thermal crosslinking agents When the positive C-type retardation layer is a cured product of a thermosetting liquid crystal composition containing a vertically aligning liquid crystal component, a photoalignable component, and a thermal crosslinking agent, a thermal crosslinking agent is used to form the positive C-type retardation layer. The thermal crosslinking agent may be a thermal crosslinking agent that bonds with the thermal crosslinking group of the thermal crosslinking structural unit. The thermal crosslinking agent can improve heat resistance and solvent resistance by bonding with at least the thermal crosslinking group of the copolymer. In addition, the thermal crosslinking agent can also bond with the side-chain liquid crystal polymer (A) containing a thermal crosslinking group in its side chain, which may be optionally contained, or a compound having a thermal crosslinking group, thereby improving the durability of the cured film and contributing to improving the functions of each.

[0125] As the thermal crosslinking agent, a compound that bonds with the thermal crosslinkable group of the thermal crosslinkable structural unit is selected and used. Examples of such thermal crosslinking agents include compounds having a crosslinking group that can react with the thermal crosslinking group. Examples of the crosslinking group that the thermal crosslinking agent has include an epoxy group, a methylol group, an isocyanate group, a blocked isocyanate group, a carboxyl group, a protected carboxyl group, and a maleimide group. The number of crosslinking groups that the thermal crosslinking agent has is preferably two or more, and more preferably two to six. Examples of the thermal crosslinking agent include epoxy compounds, methylol compounds, and isocyanate compounds. Among these, methylol compounds are preferred in terms of the stability of the thermosetting liquid crystal composition (coating liquid) and the ability to use mild curing conditions. Specific examples of the methylol compound include compounds such as alkoxymethylated glycoluril, alkoxymethylated benzoguanamine, and alkoxymethylated melamine. Other specific examples of the thermal crosslinking agent include the thermal crosslinking agents described in paragraphs 0144 to 0148 of WO 2022 / 158555.

[0126] These thermal crosslinking agents can be used alone or in combination of two or more. In the present disclosure, from the viewpoint of improving the durability of the cured film, the content of the thermal crosslinking agent may be 0.1 to 30 parts by mass relative to 100 parts by mass of the solid content of the photoalignable thermosetting liquid crystal composition. In particular, from the viewpoint of facilitating vertical alignment of the liquid crystalline component contained in the positive A-type retardation layer in the permeated region of the present disclosure, the content is more preferably 0.5 to 25 parts by mass, and even more preferably 1 to 20 parts by mass. Furthermore, the content of the thermal crosslinking agent in the photo-alignable thermosetting liquid crystal composition of the present disclosure may be 1 to 30 parts by mass relative to 100 parts by mass of the total of the side chain liquid crystal polymer (A) and the copolymer (B). However, in the region where the composition of the present disclosure has permeated, the liquid crystal component contained in the positive A-type retardation layer is more likely to be vertically aligned, so the content is more preferably 2 to 25 parts by mass, and even more preferably 3 to 25 parts by mass, and the upper limit may be less than 10 parts by mass. If the content of the thermal crosslinking agent is too low, the heat resistance and solvent resistance of the cured film formed from the photo-alignable thermosetting liquid crystal composition may decrease, resulting in a risk of a decrease in vertical alignment property and liquid crystal alignment ability. Furthermore, if the content is too high, the vertical alignment property, liquid crystal alignment ability, and storage stability may decrease. To improve the out-of-plane retardation of the positive C-type retardation layer of the present disclosure and facilitate satisfying the condition (1), it is preferable to reduce the content of the thermal crosslinking agent within a range that allows the heat resistance of the cured film to be maintained.

[0127] The structures of the liquid crystal component, photoalignment component, and thermal crosslinker contained in the positive C-type retardation layer can be analyzed using NMR, IR, GC-MS, XPS, TOF-SIMS, or a combination of these methods. For example, material can be collected from the positive C-type retardation layer and the chemical structures of the liquid crystal component, photoalignment component, and thermal crosslinker component can be analyzed using nuclear magnetic resonance spectroscopy (NMR). Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) can also detect fragments derived from the photoalignment group. Furthermore, peaks of bonds and functional groups derived from the thermal crosslinker and photoalignment component can be confirmed using X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and Raman spectroscopy. The structure of the components contained in the positive C-type retardation layer can be analyzed by combining the results of these analyses.

[0128] 1-4. Acid or acid generator When the positive C-type retardation layer is a cured product of the thermosetting liquid crystal composition, the thermosetting liquid crystal composition may contain an acid or an acid generator, which can accelerate the thermal curing reaction of the thermosetting liquid crystal composition.

[0129] The acid or acid generator is not particularly limited as long as it is a sulfonic acid group-containing compound, hydrochloric acid or its salt, or a compound that thermally decomposes to generate an acid when the coating film is dried or heat-cured, i.e., a compound that thermally decomposes to generate an acid at a temperature of 50° C. to 250° C. Specifically, those described in paragraph 0054 of WO 2010 / 150748 can be used.

[0130] The content of the acid or acid generator in the photoalignable thermosetting liquid crystal composition of the present disclosure may be 0.01 to 20 parts by mass relative to 100 parts by mass of the solid content of the photoalignable thermosetting liquid crystal composition. In particular, the content is more preferably 0.05 to 10 parts by mass, and even more preferably 0.05 to 5 parts by mass, since the liquid crystal component contained in the positive A-type retardation layer is more likely to be vertically aligned in the permeated region of the present disclosure. The content of the acid or acid generator in the photoalignable thermosetting liquid crystal composition of the present disclosure may be 0.05 to 20 parts by mass relative to 100 parts by mass of the total of the side-chain liquid crystal polymer (A) and the copolymer (B). In particular, from the viewpoint of improving the out-of-plane retardation of the positive C-type retardation layer of the present disclosure and making it easier to satisfy the conditions (1) and (3), the content is more preferably 0.1 to 15 parts by mass, and even more preferably 0.1 to 10 parts by mass, and the upper limit may be less than 1 part by mass.

[0131] 1-5.Other ingredients The composition for the positive C-type retardation layer used in the positive C-type retardation layer may contain other components. The other components can be appropriately selected and used as long as they do not impair the effects of the present disclosure. Specific examples of the other components include other polymerizable liquid crystal compounds, polymerizable compounds having two or more polymerizable groups in one molecule to improve the hardness and durability of the coating film, photopolymerization initiators, compounds having a polymerizable group and a thermally crosslinkable group, other compounds having a photoalignment group and a thermally crosslinkable group, sensitizers, leveling agents, polymerization inhibitors, antioxidants, light stabilizers, etc. The other components may be similar to the other components described in paragraphs 0155 to 0173 of WO 2022 / 158555, for example.

[0132] The liquid crystal component and photo-alignable component used in forming the positive C-type retardation layer are not limited to the specific examples, but may be appropriately selected from conventionally known components. For example, the thermosetting liquid crystal composition having the second photoalignment property described in paragraphs 0244 to 0350 of WO 2022 / 158555 may be appropriately selected and used. In addition, in order to promote the vertical alignment of the positive C-type retardation layer, a vertical alignment promoter described in paragraphs 0100 to 0185 of WO 2013 / 100115, a liquid crystal dendrimer described in Japanese Patent No. 5717086, or the like may be used.

[0133] 1-6. Formation of positive C-type retardation layer The positive C-type retardation layer of the present disclosure can be formed, for example, by preparing a composition (coating liquid) for a positive C-type retardation layer by dissolving or diluting the components constituting the positive C-type retardation layer as described above in a solvent, and applying and drying the composition on a support.

[0134] The solvent may be the same as the solvents described in paragraphs 0153 to 0154 of WO 2022 / 158555, for example. The support may be a substrate, which will be described later, or an alignment film of a substrate provided with an alignment film, which will be described later. The coating method may be selected appropriately as long as it is a method that can form a film with a desired thickness with high precision.

[0135] The composition for a positive C-type retardation layer is applied to a support, and in the process of removing the solvent, the temperature is adjusted to a temperature at which the liquid crystal component can be vertically aligned, and then heated. Specifically, vertical alignment is induced by heating to a temperature above the liquid crystal phase transition temperature and below the isotropic transition temperature (preferably below the isotropic transition temperature). By the heat treatment, the liquid crystal portion of the liquid crystal component can be at least vertically aligned and dried, and the liquid crystal component can be fixed while maintaining the alignment state. The temperature at which vertical alignment can be achieved varies depending on the substances in the liquid crystal composition and must be adjusted appropriately. For example, the temperature may be within a range of 40°C to 200°C, or may be within a range of 40°C to 150°C.

[0136] When the composition for the positive C-type retardation layer has thermosetting properties, the more the thermosetting proceeds, the more the vertical alignment property deteriorates. Therefore, in order to improve the out-of-plane retardation of the positive C-type retardation layer and make it easier to satisfy the condition (1), it is preferable to suppress the thermosetting to an extent that the vertical alignment property does not deteriorate by reducing the amount of the thermal crosslinking agent or the amount of the acid catalyst in the composition as described above. Furthermore, in order to improve the out-of-plane retardation of the positive C-type retardation layer and facilitate the satisfaction of the conditions (1) and (3), it is preferable to perform two or more stages of temperature control in the drying process during the formation of the positive C-type retardation layer, thereby achieving both improved vertical alignment and curing. For example, the first stage of heating promotes vertical alignment of the liquid crystal while suppressing curing, and the second stage of heating promotes the curing reaction to the required degree of curing, thereby achieving both alignment and curing. The required degree of curing can be determined, for example, based on a degree that maintains good liquid crystal alignment ability and prevents the positive C-type retardation layer from being hindered from vertical alignment due to excessive penetration of the positive A-type retardation layer. Specific examples of the heating temperature include a first-stage heating temperature of 60°C to 100°C and a second-stage heating temperature of 110°C to 150°C, and further, a first-stage heating temperature of 80°C to 100°C and a second-stage heating temperature of 120°C to 140°C.

[0137] The heating time may be selected appropriately, for example, within the range of 10 seconds to 60 minutes, preferably 20 seconds to 30 minutes. For example, the heating time for the first stage can be set to within 20 seconds to 10 minutes, and the heating time for the second stage can be set to within 20 seconds to 10 minutes, or the heating time for the first stage can be set to within 30 seconds to 5 minutes, and the heating time for the second stage can be set to within 30 seconds to 5 minutes. As the heating means, for example, a hot plate, an oven, or other known heating and drying means can be appropriately selected and used.

[0138] In the positive C-type retardation layer of the present disclosure, it is preferable to further irradiate the thus obtained cured film having retardation with polarized ultraviolet light, thereby imparting liquid crystal alignment ability to the cured film. The resulting cured film can be irradiated with polarized UV light to induce a photoreaction of the photoalignment group of the photoalignment component, such as copolymer (B), thereby exhibiting anisotropy. The wavelength of the polarized UV light is typically within the range of 150 nm to 450 nm. The direction of irradiation of the polarized UV light can be perpendicular or oblique to the substrate surface. In this way, a positive C-type retardation layer can be formed to which a liquid crystal aligning ability for aligning the liquid crystal component of the positive A-type retardation layer is imparted.

[0139] 1-7. Structure of positive C-type retardation layer The positive C-type retardation layer may be a film that is cured in a state in which the liquid crystalline portion of the liquid crystalline component is vertically aligned and the photo-alignable group of the photo-alignable component present on the surface has a photo-dimerized structure or a photo-isomerized structure. When the positive C-type retardation layer contains a thermal crosslinking agent, it may have a structure containing, in one layer, a liquid crystalline component such as the vertically aligned side-chain liquid crystal polymer, a photodimerization structure or photoisomerization structure of a photoalignment group, and a crosslinked structure formed by bonding a thermal crosslinking group with a thermal crosslinking agent. Also, the positive C-type retardation layer may have a structure containing, in one layer, the vertically aligned side-chain liquid crystal polymer, and a copolymer having a photodimerization structure or photoisomerization structure of a photoalignment group in a photoalignment structural unit, and a crosslinked structure formed by bonding a thermal crosslinking group in a thermal crosslinking structural unit with a thermal crosslinking agent.

[0140] The photodimerization structure of the photoalignment group contained in the positive C-type retardation layer is, for example, a structure in which the photoalignment groups of the photoalignment structural units represented by the above formula (1) are crosslinked by a photodimerization reaction, and has a cyclobutane skeleton. The photodimerization reaction is shown below, in which the olefin structure contained in the photo-aligning group undergoes a photoreaction to form a cyclobutane skeleton. Xa to Xd and Xa' to Xd' vary depending on the type of photo-aligning group.

[0141] [ka]

[0142] The photodimerization structure is preferably a photodimerization structure of a cinnamoyl group. Specifically, a structure in which the cinnamoyl groups are crosslinked by a photodimerization reaction is preferred. In particular, it is preferred to include a photodimerization structure represented by the following formulas (x-4) and (x-5). In the following formulas, each symbol is the same as in the above formulas (x-1), (x-2), and (x-3).

[0143] [ka]

[0144] When the positive C-type retardation layer has a photodimerization structure represented by the above formulas (x-4) and (x-5), many aromatic rings are arranged and the layer contains many π electrons, which is thought to increase the affinity with the positive A-type retardation layer formed on the positive C-type retardation layer, improve the liquid crystal alignment ability, and further increase the adhesion with the liquid crystal layer.

[0145] The photoisomerizable structure is a structure in which the photoalignable group of the photoalignable structural unit is isomerized by a photoisomerization reaction. For example, in the case of a cis-trans isomerization reaction, the photoisomerizable structure may be either a structure in which a cis isomer is converted to a trans isomer or a structure in which a trans isomer is converted to a cis isomer. For example, when the photo-alignable group is a cinnamoyl group, the photoisomerization reaction is as shown below, in which the olefin structure contained in the photo-alignable group forms a cis or trans isomer by photoreaction. Xa to Xd vary depending on the type of photo-alignable group.

[0146] [ka]

[0147] The photoisomerizable structure is preferably a photoisomerizable structure of a cinnamoyl group. Specifically, a structure in which the cinnamoyl group is isomerized by a photoisomerization reaction is preferred. In this case, the photoisomerizable structure may be either a structure in which a cis isomer is converted to a trans isomer, or a structure in which a trans isomer is converted to a cis isomer. In particular, the alignment layer preferably has a photoisomerizable structure of a cinnamoyl group represented by the above formulas (x-1) and (x-2), as shown in the following formulas (x-6) and (x-7).

[0148] [ka]

[0149] When a thermal crosslinking agent is used in forming the positive C-type retardation layer, the thermal crosslinking group bonds with the thermal crosslinking agent. Therefore, the crosslinked structure is a three-dimensional network structure formed by crosslinking the thermal crosslinking group and the thermal crosslinking agent upon heating. Examples of crosslinked structures include a crosslinked structure formed by bonding a thermal crosslinking group possessed by the thermal crosslinking structural unit of the copolymer with the thermal crosslinking agent, and a crosslinked structure formed by bonding a thermal crosslinking group possessed by another component with the thermal crosslinking agent. For example, when the non-liquid crystal and thermal crosslinking structural unit of the side-chain liquid crystal polymer has a thermal crosslinking group, the crosslinked structure may include a crosslinked structure formed by bonding a thermal crosslinking group of the side-chain liquid crystal polymer with the thermal crosslinking agent. Note that the crosslinked structure does not include a structure in which photo-alignable groups are crosslinked by a photodimerization reaction, or a structure in which ethylenically unsaturated double bond groups are polymerized together. However, as long as the effect of the present invention is not impaired, the positive C-type retardation layer of the present disclosure may further contain a structure in which ethylenically unsaturated double bond groups are polymerized together. The crosslinked structure contains residues of the thermal crosslinking agent after the reaction of the thermal crosslinking agent.

[0150] The positive C-type retardation layer may further contain an acid or an acid generator, the above-mentioned other components, and decomposition products thereof.

[0151] It can be confirmed by collecting and analyzing a material from the positive C-type retardation layer that the positive C-type retardation layer contains a photo-alignment component, the photo-dimerization structure or the photo-isomerization structure, the crosslinked structure, and other components. NMR, IR, GC-MS, XPS, TOF-SIMS, and a combination thereof can be used as the analysis method.

[0152] In addition, the photo-alignment component in the positive C-type retardation layer can be confirmed by analyzing the surface of the substrate side prepared by peeling off the substrate by transfer, or the cross section prepared by cutting obliquely from the top surface of the positive C-type retardation layer to the interface between the positive C-type retardation layer and the substrate using a surface / interface cutting tester. The measurement conditions for TOF-SIMS are the same as those in the above-mentioned condition (2). The method for preparing a cross section by cutting diagonally up to the interface between the positive C-type retardation layer and the substrate involves cutting diagonally from the surface of the positive A layer of the optical laminate using a surface / interface cutting tester (SAICAS NN-04 model, manufactured by Daipla Wintes Co., Ltd.). The cutting conditions are as follows: Cutting edge: Single crystal diamond Blade width: 1mm Cutting edge rake angle: 20° Cutting edge relief angle: 10° Horizontal cutting edge speed: 400nm / sec Vertical cutting edge speed: 4nm / sec

[0153] In order to easily suppress photodegradation of optical properties, when the surface of the positive C-type retardation layer not directly adjacent to the positive A-type retardation layer is analyzed by TOF-SIMS, the maximum peak area of ​​secondary ions derived from photoalignable groups is preferably 2.5% or less, or may be 2.2% or less, of the total ion amount. The lower limit is not particularly limited, but may be 0.1% or more, or may be 0.5% or more. In addition, in order to easily suppress photodegradation of optical properties, when a region of the positive C-type retardation layer from the interface on the positive A layer side to the positive C-type retardation layer side in the thickness direction is analyzed by TOF-SIMS, the peak area of ​​the maximum secondary ion derived from the photoalignment group is preferably 2.5% or less, and may be 2.2% or less, of the total ion amount. The lower limit is not particularly limited, but may be 0.1% or more, or may be 0.5% or more.

[0154] In addition, in the retardation plate of the present disclosure, it is preferable to adjust the composite elastic modulus of the positive C-type retardation layer in order to obtain a retardation plate with good bending resistance. The composite elastic modulus of the positive C-type retardation layer may be 4.5 GPa or more and 9.0 GPa or less, 5.0 GPa or more and 8.5 GPa or less, or 5.0 GPa or more and 8.0 GPa or less. When the positive C-type retardation layer is a cured product of a thermosetting liquid crystal composition, the composite elastic modulus can be easily adjusted. The composite elastic modulus of the positive C-type retardation layer is determined by measuring the indentation hardness (H IT ) when measuring the contact projection area A p The "indentation hardness" is a value determined from the load-displacement curve from loading to unloading of the indenter obtained by hardness measurement using the nanoindentation method. The composite elastic modulus of the positive C-type retardation layer is an elastic modulus that includes the elastic deformation of the positive C-type retardation layer and the elastic deformation of the indenter.

[0155]

number

[0156] The composite elastic modulus of the positive C-type retardation layer is measured on the surface of the positive C-type retardation layer opposite to the interface with the positive A-type retardation layer. Specifically, the composite elastic modulus of the positive C-type retardation layer is determined as follows. First, the substrate of the retarder is peeled off, and the positive C-type retardation layer and the positive A-type retardation layer are transferred to adhesive glass in the order of positive C-type retardation layer / positive A-type retardation layer / adhesive glass to prepare a measurement sample. Using the measurement sample, the indentation hardness of the surface of the positive C-type retardation layer exposed by peeling off the substrate is measured. The indentation hardness (HIT) is measured for the measurement sample using a nanoindenter (BRUKER, TI950 TriboIndenter). Under the following measurement conditions, a Berkovich indenter (triangular pyramid) (e.g., BRUKER, TI-0039) is pressed vertically into the surface of the positive C-type retardation layer over 10 seconds until a maximum indentation load of 3 μN is reached. After that, the pressure is held constant to allow the residual stress to relax, and the load is released over 10 seconds to measure the maximum load after relaxation, and the maximum load Pmax (μN) and the contact projected area Ap (nm 2 ) and calculate the indentation hardness (HIT) by Pmax / Ap. The above contact projected area is the contact projected area corrected for the indenter tip curvature by the Oliver-Pharr method using a standard sample of fused quartz (e.g., 5-0098 manufactured by BRUKER). If any of the measured values ​​deviate by more than ±20% from the arithmetic mean value, that measured value is excluded and remeasured. (Measurement conditions) ·Loading speed: 0.3μN / sec ·Holding time: 5 seconds ·Loading and unloading speed: 0.3μN / sec ·Measurement temperature: 25℃

[0157] Next, the composite elastic modulus Er is calculated from the above-mentioned formula (1) using the contact projected area Ap obtained when measuring the indentation hardness (HIT) of the obtained positive C-type retardation layer. The composite elastic modulus Er is calculated by measuring the indentation hardness at 10 points, calculating the composite elastic modulus each time, and averaging the obtained composite elastic moduli at 10 points.

[0158] The thickness of the positive C-type retardation layer can be appropriately set, but is preferably 0.1 μm to 4 μm, more preferably 0.3 μm to 2 μm, in order to obtain a sufficient out-of-plane retardation Rth and easily exhibit a good birefringence index Δn in the thickness direction.

[0159] 2. Positive A-type retardation layer In the retardation plate of the present disclosure, the positive A-type retardation layer is a layer that exhibits horizontal alignment (homogeneous alignment). In the retardation plate of the present disclosure, the polymerizable liquid crystal compound contained in the positive A-type retardation layer exhibits reverse wavelength dispersion, which means a "negative dispersion" characteristic in which the longer the measured wavelength, the greater the birefringence in at least a part of the wavelength range of visible light. The reverse wavelength dispersion is confirmed by determining whether Re(450), Re(550), and Re(650) satisfy the following relationship (i): Re(450) <Re(550)<Re(650) (i)

[0160] By exhibiting reverse wavelength dispersion as a positive A-type retardation layer, it is possible to easily impart reverse wavelength dispersion to the entire optical member including the positive A-type retardation layer and the positive C-type retardation layer, and it is possible to easily improve visibility, antireflection properties, and the like in a wavelength range outside 550 nm.

[0161] Specifically, the positive A-type retardation layer preferably has Re(450) / Re(550) in the range of 0.8 to 0.9, and Re(650) / Re(550) in the range of 1.03 to 1.25.

[0162] The liquid crystal component that can be horizontally aligned may be a liquid crystal polymer or a liquid crystal monomer. The liquid crystal component having horizontal alignment properties may be a polymerizable liquid crystal compound having a polymerizable group, from the viewpoint of stability of the alignment state in the permeation region. A polymerizable liquid crystal compound having a polymerizable group can be used, and if it contains a liquid crystal compound showing reverse wavelength dispersion, a liquid crystal compound generally used for a positive A-type retardation layer can be used. Examples of the polymerizable group contained in the polymerizable liquid crystal compound include cyclic ether-containing groups such as oxirane rings and oxetane rings, and ethylenic double bond-containing groups. Among these, ethylenic double bond-containing groups are preferred because they exhibit photocurability and are easy to handle. Examples of the ethylenic double bond-containing group include vinyl groups, allyl groups, and (meth)acryloyl groups. Among these, (meth)acryloyl groups are preferred.

[0163] The polymerizable liquid crystal composition in the positive A-type retardation layer preferably contains a polymerizable liquid crystal compound that exhibits liquid crystallinity and has a polymerizable group in the molecule. As the polymerizable liquid crystal compound, a conventionally known polymerizable liquid crystal compound that exhibits reverse wavelength dispersion can be appropriately selected and used. The polymerizable liquid crystal composition may be composed of one liquid crystal compound or a mixture of two or more liquid crystal compounds.

[0164] Specific examples of the polymerizable liquid crystal compound in the positive A-type retardation layer of the present disclosure include the polymerizable liquid crystal compound represented by the following general formula (1) described in Japanese Patent No. 6473537, the polymerizable liquid crystal compound represented by the following general formula (2) described in Japanese Patent No. 5463666, and the polymerizable liquid crystal compound described in Japanese Patent No. 4186981, Japanese Patent No. 5962760, and Japanese Patent No. 5826759, Japanese Patent No. 6568103, Japanese Patent No. 6427340, JP-A 2016-166344, and Recueil des Travaux Chimiques des Pays-Bas (1996), 115 (6), 321-328. Examples of the polymerizable liquid crystal composition for the positive A-type retardation layer include compositions described in paragraphs 0133 to 0143 of JP-A No. 2014-174468 and compositions described in paragraphs 0083 to 0092 of Japanese Patent No. 6739621.

[0165] [ka] (The symbols in the general formula (1) are as described in Japanese Patent No. 6473537.)

[0166] General formula (2) P 1 -F 1 -(B 1 -A 1 ) k -E 1 -G 1 -D 1 -Ar-D 2 -G 2 -E 2 -(A 2 -B 2 ) l -F 2 -P 2 [In formula (2), Ar is any one of the divalent groups represented by formula (Ar-6) to formula (Ar-7), and the number Nπ of π electrons contained in the aromatic ring in the Ar group is 12 or more.

[0167] [ka] [In formula (Ar-6) ~ formula (Ar-7), Z 1 represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 6 carbon atoms, an alkylsulfonyl group having 1 to 6 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, an N-alkylamino group having 1 to 6 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 6 carbon atoms, or an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms. Q 1 are each independently -CR7 R 8 -, -S-, -NR 7 represents -, -CO- or -O-. R 7 and R 8 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y 2 each independently represents an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms or an optionally substituted aromatic heterocyclic group having 4 to 20 carbon atoms and containing at least one hetero atom. n represents an integer of 0 to 2. D 1 and D 2 are each independently *-O-CO- (* represents the position of bonding to Ar), -C(=S)-O-, -OC(=S)-, or -CR 1 R 2 -, -CR 1 R 2 -CR 3 R 4 -, -O-CR 1 R 2 -, -CR 1 R 2 -O-, -CR 1 R 2 -O-CR 3 R 4 -, -CR 1 R 2 -O-CO-, -O-CO-CR 1 R 2 -, -CR 1 R 2 -O-CO-R 3 R 4 -, -CR 1 R 2 -CO-O-CR 3 R 4 -, -NR 1 -CR 2 R 3 -, -CR 2 R 3 -NR 1 -, -CO-NR 1 - or -NR 1 represents -CO-. 1 , R 2 , R 3 and R 4each independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms. G 1 and G 2 each independently represents a divalent alicyclic hydrocarbon group. A hydrogen atom contained in the alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a methylene group contained in the alicyclic hydrocarbon group may be substituted with -O-, -S-, or -NH-. E 1 , E 2 , B 1 and B 2 are each independently -CR 5 R 6 -, -CH2-CH2-, -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -C(=S)-O-, -OC(=S)-, -OC(=S)-O-, -CO-NR 5 -, -NR 5 R represents -CO-, -O-CH2-, -CH2-O-, -S-CH2-, -CH2-S- or a single bond. 5 and R 6 each independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms. A 1 and A 2 each independently represent a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group. A hydrogen atom contained in the divalent alicyclic hydrocarbon group and the divalent aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group. A hydrogen atom contained in the alkyl group having 1 to 4 carbon atoms and the alkoxy group having 1 to 4 carbon atoms may be substituted with a fluorine atom. k and l each independently represent an integer of 0 to 3. F 1 and F 2each independently represents an alkylene group having 1 to 12 carbon atoms. A hydrogen atom contained in the alkylene group may be substituted with an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen atom, and a methylene group contained in the alkylene group may be substituted with -O- or -CO-. P 1 and P 2 are each independently a hydrogen atom or a polymerizable group (provided that P 1 and P 2 At least one of represents a polymerizable group.

[0168] The explanation of each symbol in the general formula (2) is as described in Japanese Patent No. 5463666, and the explanation of each symbol in the general formula (2) in Japanese Patent No. 5463666 is incorporated herein by reference. The polymerizable group in the general formula (2) is a substituent that can polymerize the compound represented by the general formula (2), and specific examples thereof include a vinyl group, a p-stilbene group, an acryloyl group, a methcroyl group, an acryloyloxy group, a methcroyloxy group, a carboxyl group, a methylcarbonyl group, a hydroxyl group, an amide group, an alkylamino group having 1 to 4 carbon atoms, an amino group, an epoxy group, an oxetanyl group, an aldehyde group, an isocyanate group, or a thioisocyanate group.

[0169] The polymerizable liquid crystal composition in the positive A-type retardation layer may further contain a photopolymerization initiator and a solvent in addition to the liquid crystal compound, and may further contain other components as described in the positive C-type retardation layer.

[0170] The positive A-type retardation layer can be formed, for example, by applying a polymerizable liquid crystal composition onto the positive C-type retardation layer which also functions as an alignment layer, heating the composition to a phase transition temperature of the polymerizable liquid crystal composition to align the liquid crystalline component, and then irradiating the coating film of the polymerizable liquid crystal composition in which the liquid crystalline component has been aligned with light.

[0171] In the step of aligning the liquid crystal component, the method for forming a coating film of the polymerizable liquid crystal composition and the method for heating to the phase transition temperature may be any conventionally known method, and are not particularly limited. The coating method and heating method can be the same as those used in the method for producing the positive C-type retardation layer.

[0172] The coating film of the polymerizable liquid crystal composition in which the liquid crystalline component is aligned is irradiated with light to cause a polymerization reaction, polymerizing the polymerizable groups of the polymerizable liquid crystal compound contained in the positive A-type retardation layer. Furthermore, when the positive C-type retardation layer contains a compound containing a polymerizable group, the polymerizable group of the compound containing a polymerizable group in the positive C-type retardation layer is polymerized with the polymerizable group of the polymerizable liquid crystal compound contained in the positive A-type retardation layer at the interface with the positive C-type retardation layer. The polymerizable group contained in the polymerizable liquid crystal compound contained in the permeation region is also polymerized with the polymerizable group of the polymerizable liquid crystal compound contained in the positive A-type retardation layer and the polymerizable group of the compound containing a polymerizable group in the positive C-type retardation layer. Any conventionally known method may be used as the light irradiation method.

[0173] 3. Base material The retardation plate of the present disclosure may include a substrate 4, for example, as shown in FIG. Examples of the substrate in the retardation plate include a glass substrate, a metal foil, a resin substrate, etc. Among them, the substrate is preferably transparent and can be appropriately selected from conventionally known transparent substrates. Examples of the transparent substrate include a glass substrate, as well as transparent resin substrates formed using resins such as acetylcellulose-based resins such as triacetylcellulose, polyester-based resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polylactic acid, olefin-based resins such as polypropylene, polyethylene, and polymethylpentene, acrylic resins, polyurethane-based resins, polyethersulfone, polycarbonate, polysulfone, polyether, polyetherketone, acrylonitrile, methacrylonitrile, cycloolefin polymers, and cycloolefin copolymers.

[0174] The transparent substrate preferably has a transmittance of 80% or more, more preferably 90% or more, in the visible light region. The transmittance of the transparent substrate can be measured according to JIS K7361-1 (Test method for total light transmittance of plastic transparent materials).

[0175] When the retardation layer is formed by a roll-to-roll method, the transparent substrate is preferably a flexible material that has flexibility so that it can be wound into a roll. Examples of such flexible materials include cellulose derivatives, norbornene-based polymers, cycloolefin-based polymers, polymethyl methacrylate, polyvinyl alcohol, polyimide, polyarylate, polyethylene terephthalate, polysulfone, polyethersulfone, amorphous polyolefin, modified acrylic polymers, polystyrene, epoxy resins, polycarbonate, and polyesters. Among these, cellulose derivatives and polyethylene terephthalate are preferably used in this embodiment. This is because cellulose derivatives have particularly excellent optical isotropy and can therefore be made to have excellent optical properties. Polyethylene terephthalate is also preferred because of its high transparency and excellent mechanical properties.

[0176] The thickness of the substrate used in this embodiment is not particularly limited as long as it is within a range that can impart the necessary self-supporting properties depending on the application of the retardation plate, but is usually within a range of about 10 μm to 200 μm. In particular, the thickness of the substrate is preferably in the range of 25 μm to 125 μm, and more preferably in the range of 30 μm to 100 μm. If the thickness is thicker than the above range, for example, when a long retardation film is formed and then cut into sheets of alignment film-cum-retardation film, processing waste may increase or the cutting blade may wear quickly.

[0177] The configuration of the substrate used in this embodiment is not limited to a configuration consisting of a single layer, and may have a configuration in which multiple layers are laminated. When multiple layers are laminated, layers of the same composition may be laminated, or multiple layers of different compositions may be laminated. For example, when the substrate further has an alignment film and the alignment film contains an ultraviolet-curable resin, a primer layer may be formed on the substrate to improve adhesion between the transparent substrate and the ultraviolet-curable resin. This primer layer may be any layer that is adhesive to both the substrate and the ultraviolet-curable resin, is visible optically transparent, and allows ultraviolet light to pass through. For example, a vinyl chloride / vinyl acetate copolymer-based layer, a urethane-based layer, or the like may be appropriately selected and used.

[0178] Furthermore, when an alignment film is not provided, an anchor coat layer may be laminated on the substrate. The anchor coat layer can improve the strength of the substrate and ensure good vertical alignment. Metal alkoxides, particularly metal silicon alkoxide sols, can be used as anchor coat materials. Metal alkoxides are usually used as alcohol-based solutions. Because the anchor coat layer needs to be a uniform and flexible film, the thickness of the anchor coat layer is preferably about 0.04 μm to 2 μm, and more preferably about 0.05 μm to 0.2 μm. When the substrate has an anchor coat layer, the adhesion between the substrate and the anchor coat layer may be improved by further laminating a binder layer between the substrate and the anchor coat layer or by incorporating a material that strengthens the adhesion to the substrate into the anchor coat layer. The binder material used to form the binder layer can be any material that can improve the adhesion between the substrate and the anchor coat layer, without any particular limitation. Examples of binder materials include silane coupling agents, titanium coupling agents, and zirconium coupling agents.

[0179] 4. Retardation plate In the retardation plate of the present disclosure, the out-of-plane retardation Rth at a wavelength of 550 nm may be −35 nm to 35 nm, the in-plane retardation Re at a wavelength of 550 nm may be 100 nm or more, and the total thickness of the positive C-type retardation layer and the positive A-type retardation layer may be 0.2 μm to 6 μm. The out-of-plane retardation Rth at a wavelength of 550 nm may be −30 nm to 30 nm, and may further be −25 nm to 25 nm. The in-plane retardation Re at a wavelength of 550 nm may be 120 nm or more, and may further be 135 nm or more. The out-of-plane retardation Rth and the in-plane retardation Re at a wavelength of 550 nm are determined by the method for measuring Δn of the positive C-type retardation layer.

[0180] The total thickness of the positive C-type retardation layer and the positive A-type retardation layer may be 0.8 μm to 5 μm, and may further be 1 μm to 4 μm. The total thickness of the positive C-type retardation layer and the positive A-type retardation layer is determined by using a scanning transmission electron microscope (STEM) described in the examples.

[0181] The retardation plate of the present disclosure has a positive A-type retardation layer directly laminated on a positive C-type retardation layer, but an alignment film may be included between the positive C-type retardation layer and the substrate. The alignment film may be a vertical alignment film because it is easy to vertically align the positive C-type retardation layer. The alignment film may be the same as that described in paragraphs 0209 to 0213 of WO 2022 / 158555. However, from the viewpoint of improving productivity, it is preferable that no alignment film is contained between the substrate and the positive C-type retardation layer, and it is preferable that a substrate is contained that is located directly adjacent to the positive C-type retardation layer.

[0182] The retardation plate of the present disclosure may further include another retardation layer. The retardation plate of the present disclosure may further contain a third retardation layer different from the positive C-type retardation layer, in which the third retardation layer, the positive C-type retardation layer, and the positive A-type retardation layer are located directly adjacent to each other in this order, and the third retardation layer may be the positive C-type retardation layer. When the third retardation layer is a positive C-type retardation layer, it is preferable to form it using the side chain liquid crystal polymer described in the positive C-type retardation layer.

[0183] The retardation plate of the present disclosure has a positive A-type retardation layer directly laminated on a positive C-type retardation layer, does not include a substrate, an alignment film, an adhesive layer, etc. for the positive A-type retardation layer, and can be made thin. The retardation plate of the present disclosure can be suitably used as an optical component in various image display devices that are intended to be thin. The retardation plate in which the positive C-type retardation layer and the positive A-type retardation layer of the present disclosure are laminated is used as a circular polarizer in a form in which a λ / 4 retardation plate and a linear polarizer are combined in an organic electroluminescence display device, for example, and is preferred from the viewpoint of being used as an external light antireflection film, and is also suitably used as a part of a polarizing plate compensation film in a liquid crystal display device.

[0184] II. Optical Components The present disclosure provides an optical member containing the retardation plate of the present disclosure and a polarizing plate. The optical member of this embodiment will be described with reference to the drawings: Figure 3 is a schematic cross-sectional view showing one embodiment of the optical member.

[0185] 3 includes the retardation plate 10 of the present disclosure and a polarizing plate 20 positioned adjacent to the retardation plate. If necessary, an adhesive layer (not shown) may be included between the retardation plate 10 and the polarizing plate 20. 3, a polarizing plate 20 is disposed on a retardation plate 10 in which the positive C-type retardation layer 1 and the positive A-type retardation layer 2 of the present disclosure are directly laminated. The polarizing plate 20 may be disposed on the positive A-type retardation layer 2 side of the retardation plate 10.

[0186] In this embodiment, the polarizing plate is a plate-like plate that transmits only light vibrating in a specific direction, and can be appropriately selected from conventionally known polarizing plates. In this embodiment, the polarizing plate may be a linear polarizing plate. The linear polarizing plate may include a plate containing a polarizer and a polarizer protective layer provided on at least one surface of the polarizer. Examples of polarizers include a stretched film or layer having an absorption anisotropic dye adsorbed thereon, and a film coated with and cured by an absorption anisotropic dye. Examples of the absorption anisotropic dye include dichroic dyes. Specific examples of the dichroic dye include iodine and dichroic organic dyes. Examples of stretched films onto which dyes having absorption anisotropy have been adsorbed include polyvinyl alcohol films, polyvinyl formal films, polyvinyl acetal films, and saponified ethylene-vinyl acetate copolymer films that have been dyed with iodine or a dye and stretched. The linear polarizer can be used, for example, by referring to paragraphs 0025 to 0059 of JP 2021-51287 A. The thickness of the polarizing plate is, for example, from 2 μm to 100 μm, and preferably from 10 μm to 60 μm.

[0187] In the present embodiment, the adhesive or pressure-sensitive adhesive for the adhesive layer (bonding layer) may be appropriately selected from conventionally known adhesives, and any adhesive form can be suitably used, such as a pressure-sensitive adhesive (adhesive), a two-component curing adhesive, an ultraviolet curing adhesive, a heat-curing adhesive, a hot-melt adhesive, etc. In the present embodiment, the adhesive or pressure-sensitive adhesive layer preferably has high transparency and durability, and further, in the second aspect of the present disclosure, the adhesive or pressure-sensitive adhesive composition is preferably one that allows the components of the retardation plate to hardly penetrate into the adhesive or pressure-sensitive adhesive layer. The pressure-sensitive adhesive or adhesive for the pressure-sensitive adhesive layer or adhesive layer may be a pressure-sensitive adhesive composition having a (meth)acrylic resin as a base polymer, or an ultraviolet-curable adhesive such as a (meth)acrylate adhesive or a vinyl ether adhesive, from the viewpoints of transparency, weather resistance, heat resistance, difficulty of component penetration, etc. The thickness of the adhesive layer (bonding layer) is determined depending on the adhesive strength and the like, and may be, for example, 1 μm to 50 μm, preferably 2 μm to 45 μm, more preferably 3 μm to 40 μm, and even more preferably 5 μm to 35 μm.

[0188] The optical member of this embodiment preferably has a reflectance Y(SCI) of 4.50% or less, more preferably 4.30% or less, and even more preferably 4.20% or less. The reflectance of the optical member of this embodiment is measured by peeling off the substrate adjacent to the positive C-type retardation layer, and using an aluminum plate having an average spectral reflectance of 20% at wavelengths of 380 nm or more and 780 nm or less as a measurement sample, and measuring the reflectance Y(SCI) with a reflectance measuring device under the following measurement conditions. ·Measurement method: Reflection SCI (measurement diameter φ8mm) ·Light source: D65 Observation angle: 10° ·Measurement items: XYZ color system Zero calibration and white calibration are performed in accordance with JIS Z 8722

[0189] The optical member of the present embodiment may further include, in addition to the polarizing plate, other layers that are included in known optical members. Examples of such other layers include, but are not limited to, a retardation layer different from the retardation layer of the present embodiment, an antireflection layer, a diffusion layer, an antiglare layer, an antistatic layer, a protective film, and the like.

[0190] The optical member of the present embodiment can be suitably used, for example, as a circular polarizing plate.The optical member of the present embodiment can be suitably used, for example, as an optical member for suppressing external light reflection in a light-emitting display device.

[0191] III. Manufacturing method for optical components The present disclosure also provides a method for manufacturing a polarizing plate, comprising: preparing a retardation plate according to the present disclosure; and laminating a retardation plate and a polarizing plate. In the method for producing an optical member according to the present disclosure, the steps may be performed in any order. For example, the retardation plate of the present disclosure may be prepared by performing a step of preparing a polarizing plate and forming the retardation plate of the present disclosure on the polarizing plate. In this case, the step of laminating the retardation plate and the polarizing plate proceeds simultaneously with the step of preparing the retardation plate.

[0192] 1.Preparing the polarizing plate For example, a polarizing plate can be prepared by using a stretched film adsorbed with a dye having absorption anisotropy as a polarizer. The stretched film adsorbed with a dye having absorption anisotropy can usually be produced by uniaxially stretching a polyvinyl alcohol-based resin film, dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, treating the polyvinyl alcohol-based resin film with the adsorbed dichroic dye with a boric acid aqueous solution, and washing the film with water after the boric acid aqueous solution treatment. A polarizer protective layer can be attached to one or both sides of the obtained polarizer to prepare a polarizing plate. The polarizing plate can be prepared, for example, by referring to paragraphs 0025 to 0059 of JP 2021-51287 A.

[0193] 2. Step of preparing the retardation plate The step of preparing the retardation plate of the present disclosure is not particularly limited as long as the retardation plate of the present disclosure can be prepared. The step of preparing the retardation plate of the present disclosure can be performed in the same manner as in the above-described method for producing a retardation plate. For example, a step of forming a film of a composition for a positive C-type retardation layer, the composition comprising: a side-chain liquid crystal polymer having a liquid crystalline structural unit containing a liquid crystalline moiety in a side chain; a copolymer having a photoalignable structural unit and a thermally crosslinkable structural unit containing a thermally crosslinkable group in a side chain; and a thermal crosslinking agent that bonds with the thermally crosslinkable group of the thermally crosslinkable structural unit; a step of heating the film-formed composition to form a cured film having a retardation; a step of irradiating the cured film having retardation with polarized ultraviolet light to form a positive C-type retardation layer having liquid crystal alignment ability; a step of applying a polymerizable liquid crystal composition for forming a positive A-type retardation layer onto the positive C-type retardation layer to form a coating film of the polymerizable liquid crystal composition, and heating the coating film to a phase transition temperature of the polymerizable liquid crystal composition to align liquid crystal molecules in the polymerizable liquid crystal composition by the positive C-type retardation layer; The method may further include a step of irradiating the coating film of the polymerizable liquid crystal composition in which the liquid crystal molecules are aligned with light to cure the composition, thereby forming a positive A-type retardation layer.

[0194] When preparing the retardation plate, it is preferable to form a positive C-type retardation layer and a positive A-type retardation layer on a substrate that can be peeled off later. The releasable substrate can be appropriately selected so as to be releasable. The substrate may be surface-treated, may be release-treated, or may have a release layer formed thereon.

[0195] 3. Step of laminating the retardation film and the polarizing film In the step of laminating the retardation plate and the polarizing plate, the retardation plate and the polarizing plate may be bonded to each other with an adhesive layer (adhesive layer). Alternatively, the retardation plate may be formed directly on the polarizing plate as described above, so that the retardation plate and the polarizing plate are laminated at the same time as the retardation plate is prepared. The adhesive layer (bonding layer) may be the same as that described above.

[0196] When the retardation plate and the polarizing plate are laminated, the angle formed by the slow axis of the positive A-type retardation layer in the retardation layer and the absorption axis of the polarizing plate is preferably 45°±5°. The polarizing plate may be disposed on the positive A-type retardation layer side of the retardation plate.

[0197] The step of laminating the retardation plate and the polarizing plate may include a step of irradiating light from the polarizing plate side. The step of laminating the retardation plate and the polarizing plate may include a step of laminating a polarizing plate on a surface of the retardation plate on the positive A-type retardation layer side, and irradiating the retardation plate with light from the positive A-type retardation layer side. When the polarizing plates are laminated using an ultraviolet-curable adhesive as a pressure-sensitive adhesive layer (adhesive layer), the step of irradiating with light from the polarizing plate side may be performed simultaneously with the step of curing the ultraviolet-curable adhesive. The amount of light irradiation may be appropriately selected, and the cumulative exposure amount at an ultraviolet wavelength of 365 nm is, for example, 400 mJ / cm 2 More than 1000mJ / cm 2 It is preferable that the content is within the following range.

[0198] In the step of laminating the retardation plate and the polarizing plate, when the retardation plate and the polarizing plate are bonded together with an adhesive layer (adhesive layer), it is preferable to peel off the substrate of the retardation plate after bonding. By peeling off the substrate of the retardation plate later, an optical member including only the polarizing plate and the positive C-type retardation layer and the positive A-type retardation layer of the retardation plate of the present disclosure can be obtained.

[0199] IV.Display device The display device of the present disclosure is characterized by including the retardation plate of the present disclosure or an optical member containing the retardation plate and a polarizing plate. Examples of the display device include, but are not limited to, a light-emitting display device and a liquid crystal display device. The display device may be a touch panel equipped with a touch sensor. The display device may also be a flexible display device.

[0200] The display device of the present disclosure is preferably a light-emitting display device. The retardation plate or the optical member of the present disclosure has the effect of improving the viewing angle while suppressing external light reflection, particularly in a light-emitting display device such as an organic light-emitting display device having a transparent electrode layer, a light-emitting layer, and an electrode layer in this order.

[0201] The display device of the present disclosure is preferably a flexible display device. Since the retardation plate or the optical member according to the present disclosure, which can be thinned and has good adhesion and bending resistance, is provided, the flexible display device has an effect of improving bending resistance. The flexible display device may be a foldable display device. In the display device of the present disclosure, configurations other than the retardation plate or the optical member may be appropriately selected publicly known configurations.

[0202] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included within the technical scope of the present disclosure. [Example]

[0203] The present disclosure will be described in more detail below with reference to examples and comparative examples. In this specification, various parameters are values ​​measured at a temperature of 25°C ± 2°C and a relative humidity of 40% to 65%, unless otherwise specified. Furthermore, before starting each measurement, the target sample is exposed to the above atmosphere for 30 minutes or more before measurement and evaluation.

[0204] (Synthesis Example 1: Synthesis of Liquid Crystal Monomer I-1) 4'-cyano-4-{4-[2-(acryloyloxy)ethoxy]benzoate} was obtained by referring to paragraphs 0121 to 0124 of WO 2018 / 003498.

[0205] (Synthesis Example 2: Synthesis of Liquid Crystal Monomer I-2) With reference to paragraphs 0127 to 0130 of WO 2018 / 003498, 4-[(4-propoxycarbonylphenyloxycarbonyl)phenyl-4-[6-(acryloyloxy)hexyloxy]benzoate was obtained.

[0206] Stearyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the non-liquid crystal monomer II-1. In addition, 2-hydroxyethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) was used as the non-liquid crystal monomer II-2tc having a thermal crosslinkable group.

[0207] (Synthesis Example 3: Synthesis of Photo-Orientable Monomer III-1) Photoalignment monomer III-1 shown in Table 2 was synthesized in the same manner as in Photoalignment Monomer 3 of Synthesis Example 3 of Japanese Patent No. 5626492.

[0208] (Synthesis Example 4: Synthesis of Photo-Orientable Monomer III-2) Photoalignment monomer III-2 shown in Table 2 was synthesized in the same manner as in Photoalignment Monomer 8 of Synthesis Example 8 of Japanese Patent No. 5626492.

[0209] (Synthesis Example 5: Synthesis of Photo-Orientable Monomer III-3) Photoalignment monomer III-3 shown in Table 2 was synthesized in the same manner as in photoalignment monomer II-1 of Synthesis Example II-9 in paragraph 0453 of WO 2022 / 158555.

[0210] (Synthesis Example 6: Synthesis of Photo-Orientable Monomer III-4) The photoalignable monomer III-4 shown in Table 2 was synthesized in the same manner as the monomer mA-9 in paragraph 0133 of WO 2021 / 167075.

[0211] (Synthesis Example 7: Synthesis of Photo-Orientable Monomer III-5) Photoalignable monomer III-5 shown in Table 2 was synthesized in the same manner as in Compound (10) of Synthesis Example 2 in paragraph 0065 of WO 2013 / 081066.

[0212] In addition, 4-hydroxybutyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) was used as the thermal crosslinkable monomer IV-1. In addition, the thermally crosslinkable monomer IV-2 shown in Table 2 was synthesized in the same manner as the non-liquid crystal monomer II-8tc having a thermally crosslinkable group in Synthesis Example II-5 of paragraph 0447 of WO 2022 / 158555. As a third component monomer, N-(methoxymethyl)methacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as a thermally crosslinkable monomer IV-3 having a self-crosslinking group.

[0213] (Production Examples A1 to A3: Production of Side Chain Liquid Crystal Polymers A1 to A3) The liquid crystal monomer I-1 and the non-liquid crystal monomers II-1 and II-2tc were combined according to Table 1 to synthesize a side chain liquid crystal polymer. A synthesis example of the side chain type liquid crystal polymer A2 will be specifically described. Non-liquid crystal monomer II-1 and non-liquid crystal monomer II-2tc were combined in a molar ratio of 50:50, and the sum of these non-liquid crystal monomers was combined with liquid crystal monomer 1 in a molar ratio of 40:60. N,N-dimethylacetamide (DMAc) was added and stirred at 40°C until dissolved. After dissolution, the mixture was cooled to 24°C, and azobisisobutyronitrile (AIBN) was added and dissolved at the same temperature. The reaction solution was added dropwise to DMAc heated to 80°C over 30 minutes, and after the addition, the mixture was stirred at 80°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and then added dropwise to another container containing stirred methanol and stirred for 20 minutes. The supernatant was removed, and the slurry was filtered. The resulting crude product was again stirred in methanol for 20 minutes, the supernatant was removed, and the mixture was filtered. The obtained crystals were dried to obtain a side-chain liquid crystal polymer A2 in a yield of 76.5%. The side-chain liquid crystal polymer thus obtained was subjected to measurement of the weight average molecular weight and structural analysis. The mass-average molecular weight measurements were performed using an HLC-8220GPC manufactured by Tosoh Corporation, with N-methylpyrrolidone containing 0.01 mol / L of lithium bromide as the eluent, polystyrene standards for the calibration curve of Mw 377,400, 210,500, 96,000, 50,400, 206,500, 10,850, 5,460, 2930, 1,300, and 580 (all manufactured by Polymer Laboratories, Easi PS-2 series) and Mw 1,090,000 (manufactured by Tosoh Corporation), and two TSK-GEL ALPHA-M columns (manufactured by Tosoh Corporation). Furthermore, it was confirmed by Py-GC-MS or MALDI-TOFMS that the polymer contained constitutional units derived from one, two or three of the non-liquid crystal monomers used.

[0214] [Table 1]

[0215] (Production Examples B1 to B7: Production of Copolymers B1 to B7) The photoalignable monomers III-1 to III-5, the thermally crosslinkable monomers IV-1 and IV-2, and the third component monomer were combined according to Table 2 to synthesize a copolymer (B). A synthesis example of copolymer B1 will be specifically described. 3.08 g of photo-alignable monomer III-1, 1.44 g of thermally crosslinkable monomer IV-1 (4-hydroxybutyl acrylate), and 50 mg of α,α'-azobisisobutyronitrile (AIBN) as a polymerization catalyst were dissolved in 25 ml of dioxane and reacted at 90 ° C for 6 hours. After the reaction was completed, the copolymer B1 was obtained by purifying it by reprecipitation. The mass average molecular weight of the obtained copolymer B1 was 15,000. The mass average molecular weight (hereinafter referred to as Mw) of each synthesized copolymer was calculated by gel permeation chromatography (GPC) using an HLC-8220 GPC manufactured by Tosoh Corporation, polystyrene as a standard substance, and NMP as an eluent.

[0216] [Table 2]

[0217] [Production Examples 1 to 11: Preparation of compositions for positive C-type retardation layer (thermosetting liquid crystal compositions having photoalignment properties) 1 to 11] The side chain type liquid crystal polymer and the photo-alignable copolymer shown in Table 3 were mixed in the mass ratio shown in Table 3 to prepare a composition for a positive C-type retardation layer (a thermosetting liquid crystal composition having photo-alignment properties) having the composition shown below. Composition of side-chain liquid crystal polymer and photo-alignable copolymer shown in Table 3: 100 parts by mass Thermal crosslinking agent (hexamethoxymethylmelamine, HMM): 5 parts by mass p-Toluenesulfonic acid monohydrate (PTSA): 0.5 parts by mass Propylene glycol monomethyl ether (PGME): 170 parts by weight Cyclohexanone: 400 parts by mass

[0218] [Table 3]

[0219] [Production Example 12: Preparation of composition 1 for positive A-type retardation layer] 100 parts by weight of the following polymerizable liquid crystal compound (LC-1) produced according to the method described in JP 2010-31223 A was mixed with 0.1 parts by weight of a polyacrylate compound (leveling agent) (BYK-361N; manufactured by BYK-Chemie), 5 parts by weight of an oxime-based photopolymerization initiator (ADEKA ARCLES NCI-930 (manufactured by ADECA Corporation)), and 1.0 parts by weight of 2,6-bis(1,1-dimethylethyl)-4-methylphenol (manufactured by Tokyo Chemical Industry Co., Ltd.). Furthermore, N-methyl-2-pyrrolidone (NMP) was added to the mixture so that the solids concentration was 13%, and the mixture was stirred at 80 ° C. for 1 hour to prepare a positive A-type retardation layer composition 1.

[0220] [ka]

[0221] [Examples 1 to 11: Production of retardation plates] (1) Positive C-type retardation layer: Formation of alignment layer and retardation layer One of the compositions 1 to 11 for positive C-type retardation layer shown in Table 4 was applied to one side of a PET substrate (manufactured by Toyobo Co., Ltd., E5100, thickness 38 μm) using a bar coater so that the layer thickness after curing would be 0.6 μm, and the coating was dried in an oven at 90°C for 1 minute, then heated in an oven at 120°C for 1 minute to align the liquid crystal component and heat cure, thereby forming a cured film having retardation. Then, polarized ultraviolet light containing a 313 nm emission line was applied to the surface of this cured film at 100 mJ / cm using an Hg-Xe lamp and a Glan-Taylor prism in a direction perpendicular to the substrate normal. 2 By irradiating the cured film, a positive C-type retardation layer (which also functions as an alignment layer) was formed on the substrate, further imparting a function as an alignment layer to the cured film. (2) Formation of a positive A-type retardation layer On the positive C-type retardation layer (which also doubles as an alignment layer and retardation layer), the composition 1 for the positive A-type retardation layer was applied by bar coating so that the film thickness after curing would be 1 μm, and after drying at 120°C for 90 seconds, ultraviolet (UV) was irradiated at a dose of 300 mJ / cm using an H bulb manufactured by Fusion. 2 A positive A-type retardation layer was formed by irradiating the light with a 1000 .mu.m wavelength of 1000 nm to prepare a retardation plate.

[0222] [Comparative Example 1] Referring to paragraphs 0107 to 0108 of JP 2022-003361 A, a monomer 1 represented by the following formula (30) and a monomer 2 represented by the following formula (31) were synthesized, and a comparative copolymer C1 was obtained in the same manner as the polymer 1 described in paragraph 0109, using the monomers 1 and 2 in a molar ratio of 3:7.

[0223] [ka]

[0224] In the same manner as in Example 1 described in paragraph 0113 of JP-A No. 2022-003361, a coating liquid 1 (C1) for a positive C layer was prepared, and a positive C-type retardation layer was produced. Subsequently, in the same manner as in Example 1(2) of the present specification, a positive A-type retardation layer was formed using the composition 1 for a positive A-type retardation layer, to produce a retardation plate.

[0225] Comparative Example 2 With reference to paragraphs 0095 to 0102 of WO 2022 / 018995, the following monomers A, C, and D were synthesized, and the comparative polymer C2 was obtained by using the monomers C, A, and D in a molar ratio of 5:95:60 in the same manner as in the copolymer 2-1 described in paragraph 0107. Also, the comparative polymer C3 was obtained by using the monomer C and the non-liquid crystal monomer II-2tc in a molar ratio of 75:25 in the same manner as in the copolymer 3-1 described in paragraph 0109.

[0226] [ka]

[0227] In the same manner as in Example 3 described in paragraph 0118 of International Publication No. 2022 / 018995, a solution was prepared by mixing comparative polymer C2 and comparative polymer C3 in a weight ratio of 10:1, and a positive C-type retardation layer was produced. Subsequently, in the same manner as in Example 1(2) of the present specification, a positive A-type retardation layer was formed using the composition 1 for a positive A-type retardation layer, to produce a retardation plate.

[0228] Comparative Example 3 The composition for forming the first optically anisotropic layer described in Example 2 of paragraph 0155 of WO 2021 / 167075 was applied to one side of a triacetyl cellulose resin film (TAC) substrate (Fujifilm Corporation, TD80UL, thickness 80 μm), and then heating, cooling, ultraviolet irradiation, and annealing were performed in the same manner to produce a positive C-type retardation layer. Subsequently, in the same manner as in Example 1(2) of the present specification, a positive A-type retardation layer was formed using the composition 1 for a positive A-type retardation layer, to produce a retardation plate.

[0229] Comparative Example 4 A second optically anisotropic layer described in Example 1 of paragraphs 0134, 0136-0138, and 0148-0155 of WO 2022 / 071410 was prepared on one side of a triacetyl cellulose resin film (TAC) substrate (FUJIFILM Corporation, TD80UL, thickness 80 μm) to prepare a positive C-type retardation layer. Subsequently, in the same manner as in Example 1(2) of the present specification, a positive A-type retardation layer was formed using the composition 1 for a positive A-type retardation layer, to produce a retardation plate.

[0230] Comparative Example 5 An alignment layer and retardation layer was formed in the same manner as in Example 1 described in paragraphs 0425, 0429, and 0437 of WO 2022 / 158555, and a positive C-type retardation layer was produced. Subsequently, a positive A-type retardation layer was formed using composition 1 for a positive A-type retardation layer in the same manner as in Example 1(2) of the present specification, and a retardation plate was produced.

[0231] [evaluation] The obtained retardation plate was evaluated as follows. In this disclosure, various parameters are values ​​measured at a temperature of 25°C ± 2°C and a relative humidity of 40% to 65%, unless otherwise specified. Furthermore, before starting each measurement, the target sample is exposed to the above atmosphere for 30 minutes or more before measurement and evaluation. Furthermore, in this disclosure, various parameters refer to the average values ​​of measurements taken at 16 locations unless otherwise specified. The 16 measurement locations are defined as follows: a 1 cm margin from the outer edge of the measurement sample, and lines are drawn to divide the area inside the margin into five equal parts vertically and horizontally. The measurement centers are the 16 intersections of these lines. If the measurement sample is rectangular, a 1 cm margin from the outer edge of the rectangle is defined as the margin, and measurements are taken at 16 intersections of the lines dividing the area inside the margin into five equal parts vertically and horizontally, and the average value is calculated. If the measurement sample is a shape other than a rectangle, such as a circle, ellipse, triangle, or pentagon, a rectangle with the largest area inscribed within the shape is drawn, and 16 measurements are taken on the rectangle using the above method.

[0232] (1) Thickness measurement of the retardation layer The thickness of the retardation layer was determined by photographing a cross section of the retardation layer using a scanning transmission electron microscope (STEM) (Hitachi High-Technologies Corporation, product name "S-4800"), measuring the thickness of the positive C-type retardation layer and the positive A-type retardation layer at 10 points on the cross-sectional image, and calculating the arithmetic mean value of the thicknesses at those 10 points. The permeation region was observed as the area where both fragments derived from the components contained in the positive A-type retardation layer and fragment ions derived from the components contained in the positive C-type retardation layer were detected by TOF-SIMS, and was included in the thickness of the positive C-type retardation layer. Cross-sectional photographs of the retardation layer were taken as follows. First, a sample cut into 1 mm × 10 mm pieces was embedded in embedding resin to prepare a block. From this block, uniform, hole-free sections with a thickness of 70 nm to 100 nm were cut using a standard sectioning method. An ultramicrotome (Leica Microsystems, EM UC7) was used to prepare the sections. These uniform, hole-free sections were used as measurement samples. Cross-sectional photographs of the measurement samples were then taken using a scanning transmission electron microscope (STEM). STEM observations were performed using a "TE" detector, an accelerating voltage of 30 kV, and an emission current of 10 μA. The magnification was adjusted from 5,000x to 200,000x, adjusting the focus and contrast and brightness to determine whether each layer could be distinguished.

[0233] (2) Alignment of positive A-type retardation layer A positive C-type retardation layer and a positive A-type retardation layer were transferred to adhesive glass, and the PET substrate was peeled off to prepare a measurement sample in the following order: positive C-type retardation layer / positive A layer / adhesive glass. An optical adhesive (Panac Corporation, Panaclean PD-S1, 25 μm, acrylic adhesive) was used for the adhesive. The alignment state of the positive A-type retardation layer of the measurement sample was observed under a polarizing microscope (Olympus Corporation, BX-51) at 200x magnification, and evaluated as follows. (Evaluation criteria for orientation) A: Uniform orientation is observed visually, and 90% or more is oriented under polarizing microscope observation. B: Visually, the orientation is not as good as that of A, and the orientation area is 50% or more but less than 90% under polarizing microscope observation. C: No orientation to the naked eye, and the orientation area under polarizing microscope observation is less than 50%

[0234] (3) Thickness direction retardation Rth and in-plane retardation Re The thickness direction retardation Rth and in-plane retardation Re at a wavelength of 550 nm were measured for the measurement sample prepared in evaluation (2) using a retardation measurement device (RETS-100, manufactured by Otsuka Electronics Co., Ltd.). The conditions for measuring the phase difference were as follows: (A1) First, to stabilize the RETS-100 light source, the light source was left on for 60 minutes or more. After that, the rotating analyzer method was selected, and the θ mode (a mode for measuring angular phase difference and calculating Rth) was selected. By selecting this θ mode, the stage becomes a tilting rotation stage. (A2) Next, the following measurement conditions were input into the RETS-100. (Measurement conditions) Retardation measurement range: Rotating analyzer method Measurement spot diameter: φ5mm Tilt angle range: -40° to 40° Tilt step: 10° Measurement wavelength range: 400nm to 800nm Average refractive index of the layer to be measured: The measurement sample was measured using an Abbe refractometer (manufactured by Atago Co., Ltd.) in accordance with JIS K7142 using sodium D line (589 nm) as a light source, and the measured value (average refractive index) was entered. Thickness: The total thickness of the positive C-type retardation layer and the positive A-type retardation layer measured in evaluation (1) was entered. (A3) Next, background data was obtained without placing a sample in the device, which was a closed system, and this was performed every time the light source was turned on. (A4) Then, the sample was placed on the stage inside the device and measured.

[0235] The out-of-plane retardation Rth of the positive C-type retardation layer was calculated from the thickness of the positive C-type retardation layer measured in the evaluation (1) and the Rth and Re of the retardation plate according to the following formula. Out-of-plane retardation Rth (nm) of positive C-type retardation layer = out-of-plane retardation Rth (nm) of retardation plate - (in-plane retardation Re (nm) / 2) As described above, the out-of-plane retardation Rth of the positive A-type retardation layer can be estimated as = the in-plane retardation Re / 2 of the positive A-type retardation layer. Since the in-plane retardation of the positive C-type retardation layer is much smaller than that of the positive A-type retardation layer, the in-plane retardation of the retardation plate can be regarded as the in-plane retardation Re of the positive A-type retardation layer. Using the calculated out-of-plane retardation Rth of the positive C-type retardation layer, Δn of the positive C-type retardation layer was calculated according to the following formula. Δn = out-of-plane retardation Rth (nm) of positive C-type retardation layer / thickness of positive C-type retardation layer (nm)

[0236] However, in Comparative Example 5, the orientation of the positive A-type retardation layer was evaluated as C in the evaluation (2), which was insufficient. Therefore, the calculation method of the out-of-plane retardation Rth of the positive C-type retardation layer shown in the evaluation (3) above could not be applied. Therefore, the Δn of the positive C-type retardation layer was calculated by the following method. Only the positive C-type retardation layer of Comparative Example 5 was separately prepared, and the film thickness and out-of-plane retardation Rth of the positive C-type retardation layer were measured in the same manner as in the above evaluations (1) and (3), and Δn was calculated.

[0237] (4) Presence or absence of a photoalignment component on the back surface of the positive C-type retardation layer (the surface not directly adjacent to the positive A-type retardation layer) The surface of the positive C-type retardation layer side of the measurement sample of the positive C-type retardation layer / positive A-type retardation layer / adhesive-attached glass was analyzed for surface components using a time-of-flight secondary ion mass spectrometer (TOF-SIMS) (TOF.SIMS5 manufactured by IONTOF). The measurement conditions were set as follows. Primary ion: Bi3 ++ Primary ion accelerating voltage: 25 kV Primary ion current value: 0.2 pA Measurement area: 300 μm x 300 μm (using a neutralization gun for charge correction) Number of scans: 64 scans The presence or absence of a photoalignment component on the surface of the positive C-type retardation layer that is not directly adjacent to the positive A-type retardation layer was confirmed based on the presence or absence of a fragment derived from the photoalignment group.

[0238] (5) Abundance of photo-alignment components on the back surface of the positive C-type retardation layer (the surface not directly adjacent to the positive A-type retardation layer) In the measurement results of the evaluation (4), the ratio of the peak area of ​​the largest secondary ion among the secondary ions derived from the photoalignable group to the total amount of ions was calculated.

[0239] (6) The abundance of photo-alignment components on the surface of the positive C-type retardation layer (the interface region directly adjacent to the positive A-type retardation layer) The positive A layer surface of the optical laminate was cut in an oblique direction using a surface / interface cutting tester (SAICAS NN-04 model, manufactured by Daipla Wintes Co., Ltd.). The cutting conditions were as follows: Cutting edge: Single crystal diamond Blade width: 1mm Cutting edge rake angle: 20° Cutting edge relief angle: 10° Horizontal cutting edge speed: 400nm / sec Vertical cutting edge speed: 4nm / sec

[0240] Next, a region of the positive C-type retardation layer, 100 nm from the interface of the positive A layer side to the positive C-type retardation layer side in the thickness direction, was analyzed by TOF-SIMS in the same manner as in evaluation (4). From the measurement results, the ratio of the peak area of ​​the largest secondary ion among the secondary ions derived from the photoalignment group to the total ion amount was calculated.

[0241] (7) Change in out-of-plane retardation before and after heat resistance test The measurement sample of the positive C-type retardation layer / positive A-type retardation layer / adhesive-attached glass was left in an environment of 85° C. for 500 hours to carry out a heat resistance test. Thereafter, in the same manner as in evaluation (3), the out-of-plane retardation Rth of the measurement sample after the heat resistance test was measured, and the absolute value ΔRth of the change in the out-of-plane retardation Rth before and after the heat resistance test was calculated.b was calculated. (Evaluation criteria for heat resistance) A:ΔRth b ≦10nm B: 10nm<ΔRth b ≦15nm C:ΔRth b >15nm

[0242] (8) Change in out-of-plane retardation before and after heat and light resistance test A polarizing plate was prepared in the same manner as described in paragraphs 0082 to 0084 of Japanese Patent No. 4390117. A polarizing plate was attached to the surface of the positive C-type retardation layer of the measurement sample of the positive C-type retardation layer / positive A-type retardation layer / adhesive-backed glass using an optical adhesive (Panaclean PD-S1, manufactured by Panac Corporation) so that the slow axis direction of the positive A-type retardation layer was at 45° with respect to the absorption axis of the polarizing plate. Using an ultraviolet carbon arc light resistance tester (manufactured by Suga Test Instruments, Fade Meter), the test chamber temperature was 80°C, relative humidity was 50%, and illuminance was 500W / m 2 A light resistance test was carried out in which light emitted from a carbon arc was irradiated from the polarizing plate side under the condition of an irradiation time of 240 hours. After peeling off the polarizing plate, the out-of-plane retardation Rth was measured after the test in the same manner as in evaluation (3), and the absolute value ΔRth of the change in the out-of-plane retardation Rth before and after the light resistance test was calculated. a was calculated. (Evaluation criteria for heat and light resistance) A:ΔRth a ≦10nm B: 10nm<ΔRth a ≦15nm C:ΔRth a >15nm

[0243] [Table 4]

[0244] [Summary of results] The retardation plates of Examples 1 to 11 are retardation plates containing a positive C-type retardation layer and a positive A-type retardation layer containing a cured product of a polymerizable liquid crystal composition located directly adjacent to the positive C-type retardation layer, wherein the positive C-type retardation layer contains a photo-alignable component, the polymerizable liquid crystal compound contained in the positive A-type retardation layer exhibits reverse wavelength dispersion, the positive C-type retardation layer satisfies the condition (1), and the laminate of the positive C-type retardation layer and the positive A-type retardation layer satisfies the conditions (2) and (3). Therefore, it has been shown that the positive A-type retardation layer exhibiting reverse wavelength dispersion has good alignment and is a retardation plate with improved heat and light resistance. In contrast, in the retardation plate of Comparative Example 1 using a positive C-type retardation layer corresponding to Patent Document 2 (JP 2022-003361 A), although the alignment of the positive A-type retardation layer exhibiting reverse wavelength dispersion was good, it was shown to be a retardation plate with poor heat resistance and poor heat and light resistance. In Comparative Example 1, the positive C-type retardation layer was not cured, and it is thought to have low heat resistance. Furthermore, in Comparative Example 1, the positive C-type retardation layer is formed using a photosensitive side-chain liquid crystal polymer containing a liquid crystal component exhibiting vertical alignment and a photo-alignable component within the same polymer. Therefore, the photo-alignable component is present in excess throughout the positive C-type retardation layer, and it is thought that the optical properties are likely to fluctuate upon light irradiation due to the photosensitivity of the photo-alignable component. Furthermore, in the retardation plate of Comparative Example 2 using a positive C-type retardation layer corresponding to Patent Document 3 (WO 2022 / 018995), the alignment of the positive A-type retardation layer exhibiting reverse wavelength dispersion was inferior to that of the examples of the present invention, and it was shown to be a retardation plate with poor heat resistance and poor heat and light resistance. In Comparative Example 2, the positive C-type retardation layer was not cured, and it is thought that the solvent resistance and heat resistance were low, the optical properties were prone to change, and the heat and light resistance were also poor. Furthermore, the retardation plates of Comparative Example 3, which uses a positive C-type retardation layer corresponding to Patent Document 4 (WO 2021 / 167075), and Comparative Example 4, which uses a positive C-type retardation layer corresponding to Patent Document 5 (WO 2022 / 071410), both had good heat resistance but poor heat and light resistance. In Comparative Examples 3 and 4, the photo-alignment component is locally unevenly distributed on the surface side of the positive C-type retardation layer directly adjacent to the positive A-type retardation layer, so the optical properties are likely to fluctuate due to the influence of the photosensitive photo-alignment component upon light irradiation, and it is thought that the heat and light resistance are poor. Furthermore, in the retardation plate of Comparative Example 5 using a positive C-type retardation layer corresponding to Patent Document 6 (WO 2022 / 158555), the vertical alignment of the positive C-type retardation layer was low, and when composition 1 for a positive A-type retardation layer containing NMP as a solvent and exhibiting reverse wavelength dispersion was applied onto the positive C-type retardation layer, the vertical alignment of the positive C-type retardation layer was easily disturbed, which also caused the alignment of the photo-alignable component to be disturbed, and it is thought that this reduced the alignment of the positive A-type retardation layer.

Claims

1. A retardation plate comprising a positive C-type retardation layer and a positive A-type retardation layer located directly adjacent to the positive C-type retardation layer and containing a cured product of a polymerizable liquid crystal composition, the positive C-type retardation layer contains a photoalignment component, the polymerizable liquid crystal compound contained in the positive A-type retardation layer exhibits reverse wavelength dispersion, A retardation plate that satisfies the following conditions (1), (2), and (3): Condition (1): The birefringence Δn of the positive C-type retardation layer in the thickness direction at a wavelength of 550 nm is less than −0.

080. Condition (2): A photoalignment component is present on the surface of the positive C-type retardation layer on the side not directly adjacent to the positive A-type retardation layer. Condition (3): The absolute value ΔRth of the change in out-of-plane retardation at a wavelength of 550 nm before and after a heat resistance test (heating at a temperature of 85° C. for 500 hours) of a laminate of the positive C-type retardation layer and the positive A-type retardation layer is 15 nm or less.

2. 2. The retardation plate according to claim 1, wherein when a surface of the positive C-type retardation layer that is not directly adjacent to the positive A-type retardation layer is analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), the peak area of ​​the largest secondary ion derived from a photoalignment group is 2.5% or less of the total ion amount.

3. 3. The retardation plate according to claim 2, wherein when a region of 100 nm from the interface of the positive A layer side of the positive C-type retardation layer in the thickness direction is analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), the peak area of ​​the maximum secondary ion derived from the photoalignment group is 2.5% or less with respect to the total ion amount.

4. An optical member comprising the retardation plate according to any one of claims 1 to 3 and a polarizing plate.

5. A display device comprising the retardation plate according to any one of claims 1 to 3, or an optical member containing the retardation plate and a polarizing plate.

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